slip on/off extrusion end coupling

I'm looking for the best hardware for allowing 2040 extrusion to be joined end to end in a way that would allow easy slip on/off of one from the other. So something like a dowel tight enough that it could be glued into one of the extrusions, and then the other slipped over the glued pair allowing for a well-aligned coupling that could be fastened by a knob using one of the slots. The application is a table saw fence that will sometimes want an extension piece. I'm thinking maybe #12 sheet metal screws that could be forced into one end, and then ground down on the exposed part for a slip-fit and cut to length, cutting the head off, once installed. Or a hard wood dowel fabricated to fairly tight tolerances, though the required diameter (about .205") is a bit small to be as strong as I'd like. I may need hundreds of these. Thinking someone might have dealt with this issue before.... Thanks!