# What are these puzzle pieces for?

### Problem statement

Here are six items, bought together in a charity shop [US: thrift]. There was no documentation with them. What is the puzzle, and what is its solution?

Four of the pieces are identical of length 3, and two are identical of length 4.

### Hint to metapuzzle: show

### Restated puzzle: show

Assemble the seven things to make a symmetrical 3-dimensional structure.

### Solution to puzzle: show

We can assemble the pieces to form a regular tetrahedron of 20 spheres in a face-centred cubic closepacking.

This page describes a similar but larger puzzle, with 35 balls instead of 20. The solution is similar, and the recomended way of finding it also works for this smaller puzzle.

### Comments: show

A good but easy puzzle. I found the metapuzzle more interesting than the puzzle itself.

This is one of several pages on puzzles and metapuzzles
.