If you wear French cuffs, get a few nice pairs of cufflinks. Or hunt resale shops for vintage ones. I don't know if you can make your own.
Tie bars, chains, and pins aren't particularly in fashion right now (although tie pins and tie bar teeth damage the fabric, so watch for that), but some guys wear them. An unusual tie clip can be a nice personal statement. When I was wearing ties to work, I kept waiting for tie bars to come back into favor. I finally just started wearing what I wanted, fashion be damned. Although I was never outside for long, I hated having my tie flap in the breeze on a windy day.
Some men can get away with a nice chunky bracelet. ID bracelets can work.
I carry vintage pocket watches. Each watch has a carefully matched chain and fob. It was fun finding the right combinations.
My father wears a black onyx ring that I always wanted to inherit. I was deeply disappointed as a child when I found out that my brother would inherit all sorts of cool things from my father and I would get nothing. I particularly wanted his dress sword, his ring, and his Rolex. The sword was stolen by movers some years ago, but I assume that he still has the ring and the watch.
The ring is too chunky for my small hands, I no longer wear wrist watches, and I have my own Rolex now. But I still want his ring and watch. Go figure.