Yes you can use an old system as a template ..your new system will be made to that size and [importantly] to the same contour. You should be able to do your own bonds without any problems as you`re well -used to what`s involved and used to seeing your head shaved....that`s something many newbies find most mentally-challenging..... I certainly would not allow anything to be stuck to my head now for 3 weeks...no way. 7 -10 days is the max. in my opinion.... a regular de-bonding is required for hygiene and before the adhesive products break down and cause a tacky mess. Bobbyphilly has a vlaid point --for the sake of 200$ or so for a nice Toplace system, you can`t go wrong ! Paul.