We have about 20 board puzzles of numerous sizes. It was impossible to find a single rack that would store these lying down. The most difficult part was accommodating such a wide variety of dimensions in a large number, since most racks can accommodate similar sized puzzles, at best. I also had to be conscious of the various depths.
The design I found to work required purchasing four of these lid organizers. At $12 each, they were a bit pricey, but they fit perfect and resulted in one puzzle rack to hold all 20! The beauty of this rack is that numerous sizes can fit on one shelf.
I measured the widest puzzle and used that to guide the width at the base. I found a 2x6 scrap as the base. drilled holes at the depth and angle that would firmly support a slight tilt without bending the metal. This was the hardest part. The final part was simply zip tying an addition tier on top.
If you had more puzzles, you could probably even expand this another level!