ship1.json

{
    "name": "(TODO) Simple Ship Mk I",
    "parts": [
        {
            "type": "brain",
            "pos": [0,0]
        },
        {
            "type": "hull",
            "pos": [-1,0],
            "welds": [0]
        },
        {
            "type": "hull",
            "pos": [1,0],
            "welds": [0]
        },
        {
            "name": "leftThruster",
            "type": "thruster",
            "pos": [-1,-1],
            "rot": 0,
            "welds": [1]
        },
        {
            "name": "rightThruster",
            "type": "thruster",
            "pos": [1,-1],
            "rot": 0,
            "welds": [2]
        },
        {
            "type": "turret",
            "pos": [0,1],
            "rot": 0,
            "welds": [0]
        }
    ]
}

ship1.lua

function Update()
    if math.floor(os.clock() / 3) % 2 == 0 then
        leftThruster:SetThrust(0)
        rightThruster:SetThrust(0.5)
    else
        leftThruster:SetThrust(0.5)
        rightThruster:SetThrust(0)
    end
end