Hi andysharp -- your main question was will wearing a hair system, topper or fullcap, damage your own hair. No is the answer. Hair is dead anyway --it`s the root which is alive and keeps pushing out the hair and oils to lubricate it. Wearing only involves adhesives either in liquid form or on tapes. These will not damage your roots. Just keep your own shaved / trimmed back `` out of the way`` while wearing. Wearing full -caps presents some different issues to a topper or partial....... JRob is THE expert in that area and has left many posts here on the subject --do a search through the older posts for full info.
One thing which occurs to me with making your template would be that just at the point where your ears meet the head, I would have thought it would be better to have the perimeter of the full cap a little above that point and not `resting` just above the ear otherwise [if you think about it ] the stylist would have to cut the hair there back to literally 2 or 3 millimetres or it would be down over the ear itself --maybe I`m talking through my A...? LOL. I have yet to read through JRob`s instructions on making a fullcap template [ I have it printed off here ] but that`s one point that occured to me a while back and one which I will be paying attention to if I decide to go down the full cap route... regards, Paul.