One of my first projects was a knife sheath for a knife a friend made me a few years ago from a chainsaw bar. It's an IWB sheath with an integral J clip. The clip is pretty secure and almost invisible. The only part of the knife and sheath visible is the handle of the knife sticking up above my belt and that is easily covered by a belt. Too bad concealed fixed blades are illegal in Virginia.
The sheath was the first time I used eyelet rivets. I had to "borrow" them from my wife's craft stockpile.
For years I carried a bulky wallet even though I rarely carry cash. I finally ditched it in favor of this card holder.
It takes up about a fourth of the space. I'm a construction worker by day so I'm up and down and moving constantly. Having a big wallet tended to chafe my leg. Now I just drop the card holder and forget about it. It's comfortable enough that I quite often forget take it out of my pocket at the end of the day.
I made a cell phone case right before I got a new phone. I never completely finished the edges because I replaced the phone but it was a fun experiment. I liked the protection that it gave the phone but didn't care for how hard it was to get the phone out. For as cheap as I can buy a generic cell phone case, I don't think it's worth the trouble of trying to make them out of kydex.