In reply to Climbing_Fin:
Walls I've been to which used tape to set the problems were always uncoated, or at least not with any textured coating, on the wood. Makes a big difference for how well tape sticks.
Some walls also use a printed photo of the wall with the problems marked on it with coloured pen. Works really well once you get the hang of it and enabels you to keep huge back catalogue of boulders if you don't change the setting of the wall too often. You could also use an i-pad if you like.