Leprechaun Lock

This is a nice lock puzzle to make for St. Patrick's Day. The shackle represents the rainbow and underneath are 4 pieces of a Leprechaun's gold. In this burr lock, remove the shamrock key (12 moves), then the rainbow shackle (18 moves) to steal all the gold. 

This is a design by Christoph Lohe from 2015 called “Burr Lock B” .  I modelled the parts from the PuzzleWillBePlayed (public site), modified some parts for a Leprechaun theme and then changed the cage so the puzzle could be assembled easily. (Those straps took some time & testing)

With the 2-part cage, the user does not require a solution to put the puzzle together each time.  The back is inscribed with the outline of a shamrock, and using the clips on the side, you can remove the top and insert the parts. The video below shows how to assemble this puzzle and also contains a complete solution.

Printing Instruction:

All layer heights were 0.2mm. 3 perimeters, 4 top/bottom walls. No support except for the shackle which requires support for one leg (which is in the air). All parts can be PLA but the Straps should be PETG. You can use PLA but they will break quicker.

Straps/Clips on the side: use PETG rather than PLA as it is more pliable. I printed with a brim. It’s better if you can get away without a brim. Maybe print one as a test piece without brim to check.If needed I set my brim to 0.2mm for easier removal from the PETG.

Shackle: This is little tricky to print because one leg is up in the air. I printed several of these by using a filament change just at the boundary of the support for the leg. I printed some of the shackles with 3 color changes and some with 4. I like 4 better. That way 2 colours are exactly at the boundary of the support for the leg. I used the “Sharpie Technique” of setting the support distance to zero (soluble support) and did a filament change just when the support is finished. Then take a sharpie and color the top of the support. The sharpie ink will cause a layer that releases the next layer .. which is the start of the leg that is in the air. You might need light sanding after to clean up. You could also split the shackle in 2 in the slicer and use joints to glue together. Use 2 different rainbow colours for each half.

If you want rainbow colours they sequence:  Blue, Green(if you use 4 color), yellow, red

My shackle used 3 or 4 transparent PETG filament because I liked the look of the transparent PETG. PLA works fine for the shackle. 15-20% infill is fine. 

4 pieces: I used Polymaker Gold Silk PLA filament. I used about 50% infill to give some heft to them.

Frame Bottom: Print the bottom standing up. I put lettering on the bottom as I was using one as a prize. No support required

Frame Top: I used ironing on the top (0.2mm) just to give a better look.

Key: Easy print in PLA.

The video in the link below will introduce the puzzle, provide assembly instructions and gives a solution (although I don't recommend to view that part until you spent several days with the puzzles and can't get anywhere). This puzzle is not too tough and should be enjoyable for non-puzzlers as well as regular puzzlers.