Tips are not hard to do but they take quite a bit of time. You really don't want to use power tools once they are on the bow because a little slip up will mar the glass. I have started pre shaping the bevels on the overlays with a sander prior to gluing them to the bow. I have always used the resin type (fiberglass?) micarta for the overlays and it is pretty hard stuff. This saves a lot of time because you can get crazy with your sander or grinder and not worry about ruining anything other than an overlay. I carefully trim them just a bit large with a Dremel tool and cut off wheel after the glue is set. Yeah, I know, you don't want to use power tools once they are on the bow. Do as I say, not as I do. Then I go to work with my little file set and start shaping. Once it is close I start sanding with 120 grit and then finish with 400. The last thing that I do is to use a chainsaw file to cut the string grooves following the established grooves on the bow. It probably takes me an hour total time to preshape and glue on the overlays. If there are three layers it will take three days as I put on one layer and let the glue cure then come back the next day and add a layer. I may spend a hour or more per tip when it comes time to shape the overlay and cut the grooves.
Bowdoc did a pretty good write up on replacing tips in his 101 thread. I wish that he would drop in every now and again as he has a wealth of knowledge about repairing old bows.