Somewhere around middle-school, I came across a diagram of the classic three-piece burr puzzle.
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It looked fun, so I endeavored to make one. Unfortunately, the materials available to me then (a scrap of plywood and a janky power scroll saw) didn’t produce very good results. It worked, but was crude and wobbly. Spray painting it black didn’t help.
A couple years ago, I revisited the project, this time with 3D printing.
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Printed at Shapeways in dyed plastic, it works great. It’s kind of pricey though, running just over $90 for the three solid pieces. Similar puzzles retail for less than $5. I tried making hollow versions to lower the price, but it reduced it less than 20%, and required annoying holes to drain the trapped material.
Yes, I could just have bought one. But there’s something fun about precisely realizing something you envisioned decades ago.
Update Feb 2022
I recently printed the burr puzzle in bronze/gold/nickel plated steel from Shapeways. I shrunk the puzzle to half size to keep the cost reasonable, but did not adjust the model to account for the difference in the material tolerance. It took a fair amount of filing on the interior slots to get the pieces to fit properly.
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If made from wood, the puzzle takes time and requires tight dimensions for a proper fit. If I ever decide to build another, I think I will scale it up to double the size. Besides being an easier build, I think it would be more durable. The 3D print worked fine as expected. The one change I would make is to print in 3 different colors.