https://forum.minetest.net/viewtopic.php?f=47&t=12926

some_workbench.lua

minetest.register_node("workbench:3x3", {
	description = "WorkBench",
	tile_images = {"workbench_3x3_top.png","workbench_3x3_bottom.png","workbench_3x3_side.png"},
	paramtype2 = "facedir",
	groups = {choppy=2,oddly_breakable_by_hand=1},
	legacy_facedir_simple = true,
	sounds = default.node_sound_wood_defaults(),
	on_construct = function(pos)
		local meta = minetest.env:get_meta(pos)
		meta:set_string("formspec",
			"size[8,9]"..
			"list[current_name;table;1,1;3,3;]"..
			"list[current_name;dst;6,2;1,1;]"..
			"list[current_player;main;0,5;8,4;]")
		meta:set_string("infotext", "3x3 WorkBench")
		local inv = meta:get_inventory()
		inv:set_size("table", 9)
		inv:set_size("dst", 1)
	end,
	can_dig = function(pos,player)
		local meta = minetest.env:get_meta(pos);
		local inv = meta:get_inventory()
		if inv:is_empty("table") and inv:is_empty("dst") then
			return true
		end
		return false
	end,
	allow_metadata_inventory_move = function(pos, from_list, from_index, to_list, to_index, count, player)
		if to_list == "dst" then
			return 0
		end
		return count
	end,
	allow_metadata_inventory_put = function(pos, listname, index, stack, player)
		if listname == "dst" then
			return 0
		end
		return stack:get_count()
	end,
	allow_metadata_inventory_take = function(pos, listname, index, stack, player)
		return stack:get_count()
	end,
	on_metadata_inventory_move = function(pos, from_list, from_index,
			to_list, to_index, count, player)
		minetest.node_metadata_inventory_move_allow_all(
				pos, from_list, from_index, to_list, to_index, count, player)
		if to_list == "table" or from_list == "table" then
			local meta = minetest.env:get_meta(pos)
			local inv = meta:get_inventory()
			local tablelist = inv:get_list("table")
			local crafted = nil

			if tablelist then
				crafted = minetest.get_craft_result({method = "normal", width = 3, items = tablelist})
			end

			if crafted then
				inv:set_stack("dst", 1, crafted.item)
			else
				inv:set_stack("dst", 1, nil)
			end
		end
	end,
	on_metadata_inventory_put = function(pos, listname, index, stack, player)
		if listname == "table" then
			local meta = minetest.env:get_meta(pos)
			local inv = meta:get_inventory()
			local tablelist = inv:get_list("table")
			local crafted = nil

			if tablelist then
				crafted = minetest.get_craft_result({method = "normal", width = 3, items = tablelist})
			end

			if crafted then
				inv:set_stack("dst", 1, crafted.item)
			else
				inv:set_stack("dst", 1, nil)
			end
		end
	end,
	on_metadata_inventory_take = function(pos, listname, index, count, player)
		if listname == "table" then
			local meta = minetest.env:get_meta(pos)
			local inv = meta:get_inventory()
			local tablelist = inv:get_list("table")
			local crafted = nil

			if tablelist then
				crafted = minetest.get_craft_result({method = "normal", width = 3, items = tablelist})
			end

			if crafted then
				inv:set_stack("dst", 1, crafted.item)
			else
				inv:set_stack("dst", 1, nil)
			end
		elseif listname == "dst" then
			local meta = minetest.env:get_meta(pos)
			local inv = meta:get_inventory()
			local tablelist = inv:get_list("table")
			local crafted = nil
			local table_dec = nil

			if tablelist then
				crafted,table_dec = minetest.get_craft_result({method = "normal", width = 3, items = tablelist})
			end

			if table_dec then
				inv:set_list("table", table_dec.items)
			else
				inv:set_list("table", nil)
			end

			local tablelist = inv:get_list("table")

			if tablelist then
				crafted,table_dec = minetest.get_craft_result({method = "normal", width = 3, items = tablelist})
			end

			if crafted then
				inv:set_stack("dst", 1, crafted.item)
			else
				inv:set_stack("dst", 1, nil)
			end
		end
		return post
	end,
})

minetest.register_node("workbench:4x4", {
	description = "4x4 WorkBench",
	tile_images = {"workbench_4x4_top.png","workbench_4x4_bottom.png","workbench_4x4_side.png"},
	paramtype2 = "facedir",
	groups = {choppy=2,oddly_breakable_by_hand=1},
	legacy_facedir_simple = true,
	sounds = default.node_sound_wood_defaults(),
	on_construct = function(pos)
		local meta = minetest.env:get_meta(pos)
		meta:set_string("formspec",
			"size[8,9]"..
			"list[current_name;table;1,0;4,4;]"..
			"list[current_name;dst;6,2;1,1;]"..
			"list[current_player;main;0,5;8,4;]")
		meta:set_string("infotext", "4x4 WorkBench")
		local inv = meta:get_inventory()
		inv:set_size("table", 16)
		inv:set_size("dst", 1)
	end,
	can_dig = function(pos,player)
		local meta = minetest.env:get_meta(pos);
		local inv = meta:get_inventory()
		if inv:is_empty("table") and inv:is_empty("dst") then
			return true
		end
		return false
	end,
	allow_metadata_inventory_move = function(pos, from_list, from_index, to_list, to_index, count, player)
		if to_list == "dst" then
			return 0
		end
		return count
	end,
	allow_metadata_inventory_put = function(pos, listname, index, stack, player)
		if listname == "dst" then
			return 0
		end
		return stack:get_count()
	end,
	allow_metadata_inventory_take = function(pos, listname, index, stack, player)
		return stack:get_count()
	end,
	on_metadata_inventory_move = function(pos, from_list, from_index,
			to_list, to_index, count, player)
		minetest.node_metadata_inventory_move_allow_all(
				pos, from_list, from_index, to_list, to_index, count, player)
		if to_list == "table" or from_list == "table" then
			local meta = minetest.env:get_meta(pos)
			local inv = meta:get_inventory()
			local tablelist = inv:get_list("table")
			local crafted = nil

			if tablelist then
				crafted = minetest.get_craft_result({method = "normal", width = 4, items = tablelist})
			end

			if crafted then
				inv:set_stack("dst", 1, crafted.item)
			else
				inv:set_stack("dst", 1, nil)
			end
		end
	end,
	on_metadata_inventory_put = function(pos, listname, index, stack, player)
		if listname == "table" then
			local meta = minetest.env:get_meta(pos)
			local inv = meta:get_inventory()
			local tablelist = inv:get_list("table")
			local crafted = nil

			if tablelist then
				crafted = minetest.get_craft_result({method = "normal", width = 4, items = tablelist})
			end

			if crafted then
				inv:set_stack("dst", 1, crafted.item)
			else
				inv:set_stack("dst", 1, nil)
			end
		end
	end,
	on_metadata_inventory_take = function(pos, listname, index, count, player)
		if listname == "table" then
			local meta = minetest.env:get_meta(pos)
			local inv = meta:get_inventory()
			local tablelist = inv:get_list("table")
			local crafted = nil

			if tablelist then
				crafted = minetest.get_craft_result({method = "normal", width = 4, items = tablelist})
			end

			if crafted then
				inv:set_stack("dst", 1, crafted.item)
			else
				inv:set_stack("dst", 1, nil)
			end
		elseif listname == "dst" then
			local meta = minetest.env:get_meta(pos)
			local inv = meta:get_inventory()
			local tablelist = inv:get_list("table")
			local crafted = nil
			local table_dec = nil

			if tablelist then
				crafted,table_dec = minetest.get_craft_result({method = "normal", width = 4, items = tablelist})
			end

			if table_dec then
				inv:set_list("table", table_dec.items)
			else
				inv:set_list("table", nil)
			end

			local tablelist = inv:get_list("table")

			if tablelist then
				crafted,table_dec = minetest.get_craft_result({method = "normal", width = 4, items = tablelist})
			end

			if crafted then
				inv:set_stack("dst", 1, crafted.item)
			else
				inv:set_stack("dst", 1, nil)
			end
		end
	end,
})

minetest.register_node("workbench:5x5", {
	description = "5x5 WorkBench",
	tile_images = {"workbench_5x5_top.png","workbench_5x5_bottom.png","workbench_5x5_side.png"},
	paramtype2 = "facedir",
	groups = {choppy=2,oddly_breakable_by_hand=1},
	legacy_facedir_simple = true,
	sounds = default.node_sound_wood_defaults(),
	on_construct = function(pos)
		local meta = minetest.env:get_meta(pos)
		meta:set_string("formspec",
			"size[8,10]"..
			"list[current_name;table;0,0;5,5;]"..
			"list[current_name;dst;6,2;1,1;]"..
			"list[current_player;main;0,6;8,4;]")
		meta:set_string("infotext", "5x5 WorkBench")
		local inv = meta:get_inventory()
		inv:set_size("table", 25)
		inv:set_size("dst", 1)
	end,
	can_dig = function(pos,player)
		local meta = minetest.env:get_meta(pos);
		local inv = meta:get_inventory()
		if inv:is_empty("table") and inv:is_empty("dst") then
			return true
		end
		return false
	end,
	allow_metadata_inventory_move = function(pos, from_list, from_index, to_list, to_index, count, player)
		if to_list == "dst" then
			return 0
		end
		return count
	end,
	allow_metadata_inventory_put = function(pos, listname, index, stack, player)
		if listname == "dst" then
			return 0
		end
		return stack:get_count()
	end,
	allow_metadata_inventory_take = function(pos, listname, index, stack, player)
		return stack:get_count()
	end,
	on_metadata_inventory_move = function(pos, from_list, from_index,
			to_list, to_index, count, player)
		minetest.node_metadata_inventory_move_allow_all(
				pos, from_list, from_index, to_list, to_index, count, player)
		if to_list == "table" or from_list == "table" then
			local meta = minetest.env:get_meta(pos)
			local inv = meta:get_inventory()
			local tablelist = inv:get_list("table")
			local crafted = nil

			if tablelist then
				crafted = minetest.get_craft_result({method = "normal", width = 5, items = tablelist})
			end

			if crafted then
				inv:set_stack("dst", 1, crafted.item)
			else
				inv:set_stack("dst", 1, nil)
			end
		end
	end,
	on_metadata_inventory_put = function(pos, listname, index, stack, player)
		if listname == "table" then
			local meta = minetest.env:get_meta(pos)
			local inv = meta:get_inventory()
			local tablelist = inv:get_list("table")
			local crafted = nil

			if tablelist then
				crafted = minetest.get_craft_result({method = "normal", width = 5, items = tablelist})
			end

			if crafted then
				inv:set_stack("dst", 1, crafted.item)
			else
				inv:set_stack("dst", 1, nil)
			end
		end
	end,
	on_metadata_inventory_take = function(pos, listname, index, count, player)
		if listname == "table" then
			local meta = minetest.env:get_meta(pos)
			local inv = meta:get_inventory()
			local tablelist = inv:get_list("table")
			local crafted = nil

			if tablelist then
				crafted = minetest.get_craft_result({method = "normal", width = 5, items = tablelist})
			end

			if crafted then
				inv:set_stack("dst", 1, crafted.item)
			else
				inv:set_stack("dst", 1, nil)
			end
		elseif listname == "dst" then
			local meta = minetest.env:get_meta(pos)
			local inv = meta:get_inventory()
			local tablelist = inv:get_list("table")
			local crafted = nil
			local table_dec = nil

			if tablelist then
				crafted,table_dec = minetest.get_craft_result({method = "normal", width = 5, items = tablelist})
			end

			if table_dec then
				inv:set_list("table", table_dec.items)
			else
				inv:set_list("table", nil)
			end

			local tablelist = inv:get_list("table")

			if tablelist then
				crafted,table_dec = minetest.get_craft_result({method = "normal", width = 5, items = tablelist})
			end

			if crafted then
				inv:set_stack("dst", 1, crafted.item)
			else
				inv:set_stack("dst", 1, nil)
			end
		end
	end,
})

minetest.register_craft({
	output = '"workbench:3x3"',
	recipe = {
		{'"group:tree"','"group:tree"'},
		{'"group:tree"','"group:tree"'},
	}
})

minetest.register_craft({
	output = '"workbench:4x4"',
	recipe = {
		{'"group:wood"','"group:wood"','"group:wood"'},
		{'"group:wood"','"group:wood"','"group:wood"'},
		{'"group:wood"','"group:wood"','"group:wood"'},
	}
})

minetest.register_craft({
	output = '"workbench:5x5"',
	recipe = {
		{'"group:wood"','"group:wood"','"group:wood"','"group:wood"'},
		{'"group:wood"','"group:wood"','"group:wood"','"group:wood"'},
		{'"group:wood"','"group:wood"','"group:wood"','"group:wood"'},
		{'"group:wood"','"group:wood"','"group:wood"','"group:wood"'},
	}
})