Threaded refill cap for soap dispenser cartridge

Since refill cartridges for our soap dispenser are pretty expensive and I didn't like the soap that comes in it, I made this threaded cap. Now we can refill our cartridges with better soap and save money.

In order to make a tight seal, you will need a sealing ring with 19-21 mm inner diameter. You have to drill the container with a large step drill. The printed part needs to be glued in place. I used 5min epoxy glue.