First: I take absolutely ZERO credit for designing this. I saw it in the latest FOSSCAD package and is 'tame' enough to belong on Thingiverse. I almost designed one of these before I stumbled across the latest package. Glad I did, so I'm sharing it. All credit goes to 'crysys' of FOSSCAD!

Second: If you live in a non-free state like California, printing this could land you in jail. Then again those 10 round PS90 mags might be glued/fused shut like the 10 round MPX magazines which were designed that way so you don't modify them with a part such as this. Have fun cleaning those.

Even if you live in a semi-free state with a 31 round capacity to accommodate the most popular rifle in America: the AR-15, increasing the capacity to the originally intended 50 rounds will still be in violation. 50 rounders are readily available on the internet, but why waste a perfectly good 30 round magazine body. Check state laws before printing/manufacturing this part!

Anyways...

I was annoyed by having to compress my spring so much just to put 30 rounds in it, so I printed one of these to replace my improvised tape method of expanding the capacity to 50. The tape method was surprisingly effective and perfectly reliable. But you have a 3D printer, and this is cooler. I usually don't load all 50 because its so expensive to shoot, but the freedom to do so without ugly tape on my gun is nice. Once I graduate again and get a nice salary lol.

I haven't tested this much, but it looks pretty bulletproof, especially if you acetone/glue the two pieces together. I have not, and they have stayed in there just fine.