Parabox & (New) Melting Block Puzzle

Summary

Here are three similar puzzles with same challenge: pack the blocks inside the box - not that hard, get the job done and see the box is apparently full. Then there's one extra block with a different color, now add this block into the box - that's the challenge. It can be done honestly and fairly, no outside the box thinking required.

Sounds familiar? That's because one of the puzzle is already on this site.

Why another model? The story is long, in case you decide to skip the rest and just start printing, the recommended puzzle to print is “New Melting Block”, besides you may reuse the fancy box from Extrutim's model.

The Long Story

I stumble upon a puzzle with 6+1 pieces and a box. Although I don't know its name, the simplicity of it amazed me.

I immediately recall Puzzle Box / Block Puzzle by Extrutim, which I've been planning to print for a long time. But his puzzle have 8+1 pieces, and dimension of the base piece is not quite the same.

I contact @Extrutim hoping to find out more. He models his puzzle from a wooden puzzle, but there's still no name.

It seems the 8+1 setup puzzle is more commonly available, suddenly I get many names for it: Redstone Box, Trick Pack, Plus One Puzzle… I even get multiple online instructions to reproduce from wooden version, the measurements of pieces vary slightly.

This reminds me of a puzzle “Calibron 12”, which is published in 1933 by Theodore Edison, son of Thomas Edison. Since then many reproductions are being made, based on different measurement of the original puzzle. Turns out they all got it wrong until 2016 for the first time the original dimensions were finally known to the world. Today you can find 3D models of both right and wrong dimensions online.

I keen to model the 2 puzzles with accurate dimensions. 3D printing can reproduce it faithfully, no more dimensional drifting. It's somewhat like digital vs analog, isn't it? 

Thankfully the 2 puzzles are much younger than “Calibron 12”, and I finally get to identify them:

• 6+1 puzzle is Parabox by Nobuyuki “Nob” Yoshigahara
• 8+1 puzzle is Melting Block by Thomas O'Beirne

They dated back to 1970s-1980s

So I get original dimensions for both of them. The numbers are astonishingly beautiful. The two puzzles are similar, if you solve one you'll immediately know how to solve the other. With the correct numbers, now I appreciate their own unique beauty. For example, Parabox has only one unique solution, while Melting Block's dimension is much more deceptive.

OpenSCAD+PuzzleCAD is perfect for this job. It's actually easier to model both at once. I preserve their similarity and use the accurate numbers in the code, and let puzzlecad do the beveling etc. It's working like a charm.

Happy printing & puzzling!

Update

I just learned in recent years, around 40 years after the original, there's an improved version of Melting Block:

• New Melting Block by John Rausch

This puzzle shares the same container and some pieces with the original Melting Block, but use a different block set that consists of only 7+1 pieces. With 1 less piece than the original Melting Block, it not only achieves the same goal as original, but also reduces the number of solutions from hundreds to 2. Elegant!

I just can't resist to update the code to produce this. Essentially only 1 line of change is required. New .stl uploaded. Done.