Don`t shave your hair at all... I can only assume from the fact that you want to go Fullcap, that your growing hair is too weak/poor to enable you to wear a topper ? Do you actually really need to go Fullcap at this time ? You are quite young ...is your hair loss/thinning so severe that you actually need to consider Fullcap...... easing yourself into the wearing-world by going Topper first, is usually a lot easier...... and also a lot cheaper !!
If you really need to go Fullcap, just dampen your hair and slick it down flat....then proceed with placing your clear kitchen film onto the head ...there are Youtube videos on line showing how to make template, including Fullcap ones.....one of JRob`s is there too. In relation to the nape/neck, what I found works best for me is [ and you have to use your best estimate/judgement] I mark my neck with an eyebrow pencil, horizontally, where the hair will ` end` / sit , when the system is styled / cut -in. I then mark another parallel line above it, somewhere between half and three-quarters of an inch up...that`s where the perimeter of the system will sit...... so you`ll have 1/2 to 3/4`s of an inch of hair from there ` hanging` down......the nape can be a bit tricky to get right but if you sit in from of a large mirror and use a hand-held mirror, you can easily see the back....get your back hair trimmed / cut to the length you normally wear it and then you can mark where your perimeter will sit, as I said, half to three quarters of an inch above......... mark a line using eyebrow pencil, to follow your natural hairline and temples at the front and down in front of the ears........ when you place the film onto your head and tiw it under your chin, you can then trace that line onto the film using permanent marker before beginning to apply sellotape over it.... you don`t have to get it spot-on...you can easily ` tweak` it later by trimming off/adding more tape....... all systems come with standard 6-inch hair length unless you specify otherwise...if you plan on wearing that style as in the pics, it`s probably best to get 6.
Fullcaps take longer to make as they use twice the amount of material and time, so you could be looking at up to 10 weeks from the time you post the template...depends on how busy the factory is too, you might get it back earlier with a bit of luck. Note, you may have to pay importation tax if required/checked by customs, as it`s being imported into the E.U. from a non- E.U. country. When you have it done, pop it on your head and post some pics [ you can blank out the eye-area for privacy] ..if it needs any ` tweaking` I can mark it for you. Making a template is not so hard.....just take your time.....you may have to scrap one or two, before you are reasonably happy.... but do your best...doesn`t have to be totally down to the last millimetre...just give a reasonable impression of your head-shape and area to be covered.
Just send the pics with the order as I said in the other post.....concentrate on getting the template done and the factory will do the rest from your pics...regards.
p.s. ---John can answer your costs question better than I can....you can always e- mail him for an exact quote.