Miter Clamp
Designed to be same thickness of 3-by material (~2.5in). Has a 45 & 22.5deg angle for clamping those difficult miters. Inspired by Shaun Boyd https://www.youtube.com/watch?v=1CYkq5dBwZI - Highly recommend his channel; thanks Shaun.
The beautiful thing about this clamp is it doesn't have to be precise to be effective, but if you desire as much precision as possible then 3d printing will help with that. You can easily make this out of wood, but it's nice to have options I think.
As mentioned in the video it's recommended to clue sandpaper to the wood-side of the clamp for added friction when applying clamping pressure. Alternatively you could try printing with the "fuzzy" setting on for the outside of the print - may achieve a similar effect.
May upload additional angles/thickness if requested and as needed.