I have found a useful aid to cutting bevels. Josh Bixler has very steady accurate hands. I do not. When I am cutting a bevel, I lay a long flat thin steel rule about 1/4" or 3/16" parallel to the fold. Then I use the razor just as Josh shows but a shallower angle so that the blade stays just clear of the paper on the underside of the bevel. Then I can press the blade against the steel rule and know that I won't cut too deeply. Now my bevels more closely resemble Josh's very clean cuts. I wish I could tell you where I found my steel rule but I just found it unused one day and picked it up. It helps a lot to have some form of non-skid on the underside of the rule to prevent it slipping.