How do I clamp this frame?

[Jcrawf]

I'm making a picture frame with inward-sloping sides. Side dimensions are 8"X2".
There must be a way to clamp the thing for gluing. I've tried Bessey clamps, a regular picture-frame clamp, corner clamps, surgical tubing, etc. All slip. I'm thinking of doing one corner at a time and hiring one of the neighbor kids to hold it while the glue sets up. I'd rather not make a special fixture for this one-time project. All suggestions appreciated.
Jack

[just started]

Cut some scraps to the reverse angle and carpet tape to outside at the corners then regular framing clamps should work.

[Jcrawf]

Why didn't I think of that? Many thanks, JS.

[Uncle Cracker]

Glue, squares at corners, big rubber bands (or bicycle tube)... done.

[crokett]

I had a similar problem once. I did 4 ratcheting straps placed at the corners but wrapped front to back rather than around the circumference. I put two on parallel to each other and tightened them enough to keep the frame from spreading, then put the other two one perpendicular to the first set and tightened them. Then I adjusted for square and let it sit. It took some tweaking but the frame came out just fine.

[cabinetman]

These spring clamps are used for that type of procedure.

Or, a thin fitted splines would work. Corners could be pressed tight. For well fitted edges just taping together tightly could also work.

I've used those little spring clamps for those odd corners, and they work very well.
.