Beautiful 3d crystal puzzle I cant take all the credit for this puzzle, i saw it in an old book somewhere. It caught my eye right away because it looks nice!
The assembled puzzle:

Once i saw it, i started looking into making one for myself. As you can see, it turned out to be in metal (aluminium to be exact).
I had the opportunity to use a good mill to make it, and got the 'stock' aluminium in the local hardware store for next to nothing!
The 'stock' was a square rod of 1 meter each, so it took just under 3 of those to make it.

Just for making it available cheaper, i made 3d drawings of my version of this puzzle. There are a few variations on it, but this one can actually be extended and scaled pretty easy!!

All the parts There are quite a few parts to print for a complete puzzle: 51 pieces in total!
The complete overview as a reference:

All the measurements are made in the same units. If the base 'stock' is 10mm, then that is 1 unit. So the square stock would be 1 x 1 unit, and each block is x units wide.
for instance, the block90 t1 is then 9 units wide. All the cutouts are either 1 or 2 units wide.
The filenames are such that it tells you how wide each piece is, except for the lock piece (= 3 units wide) and the centerpieces (= 11 units wide).
If you take the drawings, then it is easy to scale things up or down.

Download files based on 10mm units:

amount	file
2	centerpiece t1
1	centerpiece t2
4	block 90 t1
2	block 90 t2
6	block 70 t1
2	block 70 t2
2	block 70 t3
10	block 50 t1
4	block 50 t2
17	block 30 t1
1	block lock

Assembly After making all the pieces, it's time to assemble!!
If you would like to try and solve it yourself first, then stop reading here.

Step	Image	action
1		First, take all centerpieces and put one centerpiece t1 ontop of t2 like shown. The cutout in t1 is pointing down.
2		Then take the second centerpiece t1, slide the other centerpiece in the cutout and slide this piece in the cutout of t2, ending as shown. Take note of where the top and bottom notches point.
3		Choose one of the centerpiece t1's and put a block90 t1 against it. Put another block90 t1 on the opposite side.
4		Take 2 blocks 70 t3 and add 4 blocks 50 t1 as shown ontop of them.
5		Add 4 blocks 30 t1 pieces as shown
6		Add 1 complete set of the previous step to the left of step 3 and also again on the opposite side.
7		Take 2 blocks 50 t2
8		Add 4 blocks 30 t1 to these as shown.
9		Add these to the puzzle like step 6
10		(image turned around for clearer view!!!). On the side of the centerpiece add the block lock as shown. mind 2 things: the side where you put the block lock and make sure it can turn. The flat middle surface should point to the center. Add a normal block 30 t1 on the opposite side.
11		take a block 90 t2
12		and add 2 block 70 t1 to is as shown
13		Add the set of the previous step as shown in the image
14		take a block 70 t2
15		add 2 block 50 t1 to it as shown
16		Add the set to the puzzle as shown
17		take a block 50 t2
18		add 2 block 30 t1 to it as shown
19		and add it to the puzzle again as shown
20		Take 1 block30 t1 and finish the side as shown
21 - 29		Repeat the steps 11 to 20 on the opposite side, ending up with the situation as shown.
30		now, locate the block lock and rotate it to make room for sliding the blocks that are positioned to the right of it.
31		Now, slide all the blocks toward the block lock, including the centerpiece. You now are able to slide all the remaining blocks in place
32-35		Slide in the blocks in order: block90 t1, block70 t1, block50 t1 and last a block30 t1. This might take a bit of jiggling, the centerpiece that is moved outward (toward the block lock) has to fit in the cutouts of the blocks you put in. Do the same thing on the opposite side.
40		Once you managed to put all the blocks in the middle, carefully slide the centerpiece in all the cutouts at the same time, then slide the other blocks that were moved toward the block lock against it. The last thing to do: rotate the block lock so it locks the puzzle. If done right, it is really hard to find that block lock again.