Back in my high school woodworking class, building a picture frame was incredibly challenging. No matter how many times I took the miters to the disc sander, the frame never hit the needed 90º. In fact, it started as an 11×14″ and ended up as an ~9.25 x 10.5″.
The frames are made from 4/4 cut to 11×14″. A 1/2″ rabbet around the inside fit layered acrylic, mat, picture, and some cardboard cut to fit. The biggest challenge with frames is the design. This one has a staggered step going around the outside and a Roman Ogee on the inside. Some 4/4 poplar cut to 1/8″ at the corners will help hold them all together. After some sanding and some tung oil, it was ready to nail some hangers on the back and stick them on the wall. Easy peasy.