A long time ago, I was fitting a beavertail and was lamenting the fact that I only had two hands and worked alone. This was a particular annoyance while trying to grind and sand the top of the beavertail to make it in register with the frame tangs. I tried all sorts of jury rigging with poor to no success to keep the beavertail swung out firmly so I could sand and grind on the top. I am definitely a "two hands on the rotary grinder kind of guy".
So one day while I was shaping a beavertail and cussing my sorry state of affairs (not having three hands) it came to me - build a tool to sit inside the frame in the trigger track that will hold the beavertail out while you grind. I did and the rest is gunsmithing history !!(I always wanted to say that)
The BT-101 tool works like you see in the attached pictures. It comes with instructions and will work with every frame and beavertail combination that I've ever exposed it to. It's made of anodized aluminum and a stainless screw and pin. Takes little room in the tool box, but does a big job.