As for triangle and hst's, Creative Grids makes specialy rulers for this. Besides the 8.5 x 24.5 ruler, the 2 triangle rulers are what I use the most. Infact, may be time to replace them.
I've used first aide tape, invisigrip, Creative Grids (the grip is part of the ruler) and a paint on product that has been the most grippy. Have loved them all.