That seems like a fun idea. I never thought about a catheter that could be mechanically opened and closed.
I've wanted to try a cath with diapers for a while, but I am afraid of A) ending up with an infection that can become very serious (and would also probably be pretty hard to explain) and B) just the pain/discomfort of having a tube go into my dick, and also the sensation of it moving or getting bumped while its still in.
I think the discomfort part might be the more significant issue in the long run. There are a lot of steps you can take to minimize the risk of infection. Wash hands, genitals, and any area covered by the diaper as well as all the areas surrounding that space very well with antibacterial of some kind before inserting and probably use something like high purity isopropol alcohol on your hands and maybe some of the less sensitive diaper areas right before, use a sealed sterile cath, drink a lot of water before putting it in, while its in, and after it comes out so that you produce a lot of pee and it flushes any bacteria out, dont keep it in too long, maybe use a diaper that is from a freshly opened pack so that nothing from the air in your house has landed on it, maybe even shine a UV light on the inside for a few minutes just before putting it on, ensure you have a healthy diet for some time before and after, getting exercise, etc. I know that none of that 100% prevents you from getting an infection, but it should certainly minimize the chance.
But the one thing any amount of hand washing wont fix is that putting something into your urethra has got to be immensely uncomfortable. The closest thing I have ever done was to poke a twisted piece of toilet paper into the tip, maybe a cm, give or take (I was a young-ish kid, not sure why I did it, guess I just wanted to see what would happen?) and I remember it being surprisingly painful. And that was a thin little strand made from toilet paper. By the looks of it, some of the tubes on caths seem pretty thick. And you dont just stick it in a tiny bit, you have to feed it all the way down the length of you dick and even further until it goes inside your bladder. (I think, right?) Also what happens if you get aroused while its in?
I would still like to try it some day, but that doesnt actually mean I will, if that makes sense.