I was a bit surprised this item was hardly to find on Thingiverse, found one but it still had is flaws and it didn't fit wel.
Everyone knows the problem after you use just used a part of your, silicone, acrylic, adhesive or any other product, that after you store it, even for a short time, the product can't be used anymore. The caps provide with some brands are nice but they not work because the air is still getting in.
So I designed a screw cap that holds an O-Ring to seal the cartridge 100% air tight.
As an extra I designed some nozzles, one with a 45o angel and so it is great to use in bathrooms and kitchens, one with a regular hole, this because the provided nozzles are weak and you know when you push a little to hard they break away from the cartridge, and the third nozzle I made with a very small hole of 1mm, I use acrylic filler for the models I make to close the seams and this nozzle works perfect.
If you have any other idea, just let me know, it's easy to make other designs.
Size of the O-Ring is 25.0 outside D - 18.6 inside D. and a thickness of 3.2 mm
Please also press LIKE when you download or collect, thanks.
Also made a watertight box for electric cables that fits, https://www.thingiverse.com/thing:3398756