Doing some decoration in my office, I had these smaller, square paintings just on particle board and no frame. Some of the other paintings I have were framed with a thick, black edge. I had some poplar around big enough to span the full edge, so I made some matching frames. This isn’t particularly complicated, but making miters sized correctly that also look pretty can be a bit fiddly.
The first step was cutting all the edges to size.
Then I used painters tape and a square to do the glue up. The painters tape did a very good job of keeping all the edges flush and applying good clamping force.
With the glue done and the frames square, next step was paiting. I just used some scrap cutoffs to stand them off my table, then spray painted them with black primer/paint spray paint (3 light coats).
I didn’t snag a picture, but once the paint dried I carefuly glued the paintings to the frames (with just some wood glue). The paintings are acrylic, so I really needed to be careful with any pressure on them. I used some paper and just weighted it down with my cordless drills and some heavy-ish tools so it was flat against the frame.
And that’s it! Finished: