So for Christmas, my GF got me a mini-Viper money clip. For probably 20+ years, I've carried a Coach magnetic folding clip. Wow - what a difference! This thing weighs nothing. It's one of those things that is so light it almost doesn't feel real. And it does a great job of holding my three dollars!
The mini-Viper Titanium Money Clip by Superior Titanium
That, combined with a Bellroy card sleeve,
Card Sleeve - Slim Leather Wallets by Bellroy
and I'm about as minimalist as I can get.