If you have an odd-sized piece, this can be a tough and expensive search. One thing you can do is find a frame that’s just slightly the wrong size (so, if your piece is a weird 22 x 33.5, you may find a frame that’s 24 x 36). If your off-the-rack frame is smaller than the piece, you can carefully trim the artwork to fit it (use a straight edge and a knife for this). If the frame you find is larger than the art, you can try to purchase a mat to cover up the space. You can also cut your own out of a large piece of mat board (available at art supply stores)…again, use a knife to cut, not scissors. Mat board is typically white-ish, but you can use paint to change the color (house paint, acrylic paint, wrap it in craft paper…anything goes). If all else fails, try a custom site like American Frame to build your own frame as cheaply as possible, or start clipping those 40% off Michael’s coupons.