Shuffler Box

First release.

Added

• Shuffler Box. A shulker box you fill with a palette of blocks. Hold it in your off hand and it keeps feeding your other hand one random block at a time out of that palette, so a wall comes out mottled without you cycling hotbar slots for an hour. Craft it from two shulker shells, a chest, a bone block and an ink sac.
• Odds set by slots, not stack sizes. Three slots of cobblestone against one of stone is three cobblestone for every stone, whether those slots hold a full stack each or a single block each. Hovering the box lists the palette as percentages.
• Odds that hold while you build. Every draw takes from the fullest slot of that block, so a slot only empties once every slot of its kind is down to its last item. A palette set to 3:1 stays at 3:1 instead of sliding to 2:1 and then 1:1 as the box drains.
• It never takes over a placement. Every block is placed out of your main hand, the ordinary way. The box only hands you the next one when a placement leaves that hand empty, so a stack you picked up on purpose -- sand to patch a floor, one particular stone -- places exactly where you point, and the box picks up again when it runs out. Right-clicking with an empty hand places a block and arms your hand, which is how you start. To place the box itself, hold it in your main hand.
• In creative it keeps itself going. Nothing is ever spent in creative, so rather than waiting for your hand to run dry the box swaps in a fresh block after each placement. Right-click once with an empty hand to start it off. A stack you picked out yourself is still left alone.
• Behaves like a shulker box otherwise. 27 slots, the vanilla shulker screen, contents kept when broken and carried, no boxes inside boxes, comparator output, and it will not be pushed by a piston.
• Places modded blocks properly. Blocks go down through the same call your own hand uses, so a modded block is placed by its own code with its data intact, and land-protection mods still get their veto.
• Create: Copycats+ support. A copycat takes its material from your off hand, which is where the box lives, so copycats get a mode of their own: hold copycat walls in your main hand with the box in your off hand, and every wall you place is filled with a material drawn from the box. Shape from your hand, paint from the box, a different material block to block. Your hand pays for the copycat, the box pays for the material, and the box only offers materials a copycat can actually wear. A blank copycat already standing in the world is painted from the box too: click it and it takes a drawn material, while one that already wears something is left alone.

Known limitations

• The palette can only be edited by placing the box, the same as a shulker box. There is no in-hand screen yet.
• Items the box cannot place, like a stack of diamonds parked in a slot, sit there unused. The tooltip says how many slots are stranded that way, but nothing stops you putting them in.
• Every texture and the icon are generated by the repo's own tooling rather than drawn by hand: functional art, not good art.