I was looking for a case to keep charging cables and adapters in my back pocket, and ended up finding that the only one that came close to standing up to a 200lb man sitting on it was this one: https://smile.amazon.com/gp/product/B00654O9AC But after a few weeks, I found that the top and bottom of the case would eventually misalign and as such, lose all its strength and get crushed. I 3D printed a positive and negative piece that would prevent lateral misalignment of the case, allowing it to keep its strength, and epoxied them into the corners with double bubble high peel epoxy. I offset by 0.005" to allow for the case to fully close, but that was on a Form 2 SLA printer, for printing with PLA you'll probably need more offset (Make the pin on the positive side smaller.) I have included the original versions. If someone figures out an optimal offset for PLA, feel free to add that model. I've included one with a 0.01 offset for PLA that may work, but is untested.