Chris Marshall: Tom, without a photo or drawing to see what sort of triangle you are trying to make, it's tough to answer your question thoroughly. Remember that wood predominantly expands across the grain, not lengthwise. And, end-grain joints are inherently weak because glue tends to wick up into the pores, forming a poor glue bond. Keep these two factors in mind when designing your triangle. If it were me, I'd try to reinforce the joints with a mechanical connection of some sort (dowels, brads, splines, screws) or choose a joint that creates its own overlapping, interlocking connection. I wouldn't count on glue to be the only hero here.