12 Bar Puzzle

I designed this puzzle from scratch, although I guess it could exist elsewhere.  The aim of the puzzle is to insert all 12 bars in to the cube such that they protrude equally on all sides, as shown in the image.

 

I printed this in Bambu Lab PLA Silk+, although other filaments should work too.  Initially any piece should slid through any hole, and it's probably worth sliding them though a few times to make sure everything works smoothly once printed.

 

Solving the puzzle (SPOILER ALERT!):

 

This isn't a complete step by step solution, but it does explain the logical thought process behind solving it.

 

There are 12 bars, and each bar partially intersects with four other bars, and the bars have various cutouts to allow other bars to slide past them, once inserted.

 

As with all similar puzzles, the last part to insert has no cutouts, and it follows that the first piece to insert must have four cutouts, as four other bars must slide past it.

 

As there is only one bar with four cutouts, it also follows that the second piece to insert must have three cutouts, and the end of it with only one cutout must intersect with the first bar inserted.  This leaves a clear hole for a third bar to slide through that intersection point.

 

The holes in the cube are not spaced the same on each axis, which means the cutouts are not spaced the same on each bar.  Comparing bar cutouts with hole spacing provides some clues as to where a bar might go.

 

If you look at the two pieces with only one cutout, you can see that in addition to the cutouts being at different positions, they are also cut at a different angle - on one the bottom of the cut is aligned with a flat side of the bar, on the other it is not.  This alignment also limits which holes a bar can go in.

 

As you insert each piece, check the holes it intersects with and make sure they are clear to allow some future piece to slide in to them.

 

The first bar to cross an intersection point must have two cutouts at that position, then second bar to cross the same intersection point must have one cutout at that position, and the third bar to cross the same intersection point must have no cutouts at that position.

 

Hopefully that's enough to get you going.  Happy puzzling!

 

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