A Christmas tree that dispenses (poops) presents. It's an unassuming tree, but push down on it, and it'll dispense a small present or lolly. The tree's mechanism is inspired by that of a click-pen, and up to five presents can be dispensed before the tree needs to be reloaded.

All parts print easily, and assembly can be completed in just a few minutes. Also, the mechanism is really easy to use - simply push down on the tree and a present will be dispensed.

Required hardware:

- 3x M3x10mm bolts.

- 1x M3x32mm bolt.

- 1x Compression spring with approximate dimensions: 5x25x0.711 mm (ODxLxID). Whatever you use, it should be stronger than an average click-pen spring. For my fellow Australians (and New Zealanders), I recommend using this spring from Bunnings: https://www.bunnings.com.au/century-spring-corp-5-x-25-4-x-0-7mm-compression-spring-6-pack_p0487964

- Some lubricant (I used MTB drivetrain lubricant, but anything found at a hardware store should suffice).

Assembly Video

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Printing Instructions:

- Base.stl: No supports.

- Central Guide.stl: Supports recommended.

- Inner Core.stl: No supports.

- Present.stl: No supports.

- Rotating Cover.stl: Supports Recommended.

- Tree Top.stl: Supports recommended.

Nozzle diameter should be 0.4 mm or less. The layer height on all moving parts (i.e., everything except for the 'tree top' and presents) should be 0.2 mm or less.

I recommend using tree supports (they will be easier to remove than standard supports).

I do not recommend removing screws from the tree once it is assembled as this may wear-out the threads.

Warning: May contain small parts. Not suitable for young children who may swallow small pieces.

Troubleshooting:

- When the central spring mechanism is assembled, the 'rotating cover' should move up and down smoothly. If this is not the case, try to work-out any printing imperfections by repeatedly pressing the cover down and letting it spring back up. Also, ensure that the 32mm screw inserted 'central guide' is as straight as possible.

- When the tree is pushed down fully, it should spring back up and reset without any user intervention. If this is not the case, ensure that the mechanism is properly lubricated (as shown in the assembly video). Also ensure that the 32mm screw that's inserted into the 'central guide' is as straight as possible.

- If the tree can be pressed all the way down, but the cover doesn't rotate, then it is likely that the thread on the 'central guide' is broken. Try reprinting this part and reassembling. To prevent this thread from wearing-down, do not disassemble the mechanism (i.e., remove the 32mm screw), and do not overtighten the 32mm screw.

This design has been a year in the making. I've trialled countless iterations of four different mechanisms to get to this point. I hope you find it as fun as I do.