place_save_button_reddit.tamper.js

// ==UserScript==
// @name         Place Save Button
// @namespace    http://tampermonkey.net/
// @version      1.0
// @description  Adds a save button to /r/place.
// @supportURL   https://www.reddit.com/message/compose/?to=TerrorBite
// @author       /u/TerrorBite
// @match        https://*.reddit.com/place
// @match        https://*.reddit.com/place?*
// @match        https://*.reddit.com/r/place/
// @grant        none
// ==/UserScript==

(function() {
    'use strict';

    // Button click handler
    var savePlaceCanvas = function() {

        // Derive filename
        var filename = "place_" + (new Date().toISOString().split('.')[0].replace(/[:-]/g,"").replace('T','_')) + ".png";

        // Obtain image as data URL
        var imageURL = $("#place-canvasse")[0].toDataURL();

        // Trigger image download
        $("<a>").attr("href", imageURL).attr("download", filename)[0].click();
    };

    // Create button and assign handler
    $('<button class="place-mute-button">').css({
        "transform":"translate(0, 48px)",
        "background-image":"none",
        "color":"white",
        "font-size":"200%"
    }).text("💾").appendTo("#place-container").click(savePlaceCanvas);

})();