For the studio project I’ve been writing about, I picked up a Johnson Sliding T-Bevel. It’s a simple tool that you can buy on Amazon for a couple bucks plus shipping. (Or, at Home Depot for around $7) Simple, yet indispensable when you need to cut trim at an angle to perfectly fit.
Basically you just place the movable blade on the angle that you are copying and tighten the wing nut. From there you can set your miter saw to match and make sure that your cut piece will fit just right.
I’m not sure how I lived for so long without this tool. However, at some point I may upgrade to a similar version that also has gauge to tell me precisely what the angle is. That would be helpful quite often as well.
Having the right tools really makes the difference sometimes!
-Peter