I received this cartridge holder for the Atari Jaguar yesterday. I have to say I have mixed feelings about it....
It does look pretty good and I like the design. However, I think it is just a smidge too small. To insert carts is difficult: I find that the slots are very, very snug. If I push a cart all the way into a slot, it takes a tremendous amount of force to pry the cart back out. The slots should really be at least a couple more millimeters wider and longer. Pretty disappointing.
I wrote to the etsy vendor, and all he wrote back was essentially, "Gosh that's too bad - for future orders we'll try printing at 101% or 102% so the carts fit better."
So, yeah, I can't recommend the vendor. If you print your own from the files on thingiverse, you might well have a better experience.