I saw this in "Ken's favorite shop tips" in The Family Handyman April 2014.
DIY Vise Clamp 90 Degree Corner Clamping Wood Work Bird House | eBay
When mounting corner blocks to reinforce a frame or case, use a clamp block on the outside to provide a flat surface for secure clamping and to prevent damage to parts. For example, to mount corner bl
In this video I make a corner clamp out of a couple of squares. The idea here was to have something that I can use to clamp 90 degree angles with. I looked i...
Learn how to cut and assemble your picture frame moldings using a specialized sled and 90-degree corner clamps.
IRWIN Tools QUICK-GRIP 90-Degree Right Angle Clamp (226410) #DIY
Jig to assist 90 degree corner clamping.
MYTEC 90 Degree Right Angle Clam DIY Picture Corner Clamp Woodworking Aluminum Kit Red
tips to make clamping dogs for making picture frames