This is a handle I designed for standard keyhole saw blades. The handle I had was "Pistol-style" and I didn't llike it. Importantly, the first finger contour has a significant projection to prevent forward slippage. Hexagonal lanyard hole also works with pegboard hooks.

Print with 3-4 shells. You may have to bend the tang of your sawblade to be flat enough to slot into the handle. Screw holes are for 3 x 1/2" 4-40 machine screws and nuts.