Good framers can make the frame to size. They have lengths of material and cut to length.
There's also a system that lets you make semi custom frames yourself. The company sells individual sides in pairs, And they're made to connect with clips that come with them. Glue, clip, wait a day and you've got a frame. I've seen the sides up to about 3 feet long and as short as I think 4 inches. And they have nice depth so you can do a nice mat and backing. The places that sell the frame bits can usually cut the glass too, my local is a framing shop that has regular, UV blocking, and "museum glass" which both blocks UV and limits glare.
It all comes out looking pretty good
Steve B
