Making wigs can be an enormous pain in the butt if you're working with a wig head that's not close to your head size. On top of that, if you have a lot of hair, are working on a wig that will be tight (like a ponytail), or resetting wefts, then having an improper size can really hurt the process and make it hard to fit into later. Having a proper wig head allows you to do all those things while also being able to ensure that your eyes are at the right place, you know where your ears are, and help you with those markers to cut at the right place.
I've made quite a few custom wigs for myself over the years, and each time I've tried a slightly different method and gotten better results. So far this is my absolute favorite method in making custom wig heads for both myself, and my clients!
Start off with a fresh head, like you would when you cosplay. Make sure your hair is recently clean, and brushed out however you would. Do all of your normal prep work to get your hair in your wig cap, such as a head band, bobby pins, ect ect. If you have to braid or straighten, do it now. You're going to want to make sure your hair is exactly how you'd put it under your wig.
The image to the left here is the markup I use when getting MOST my measurements. The list of measurements you will want to take are the following:
With a sharpie, measure from the bridge of the wig's nose between the eyes to the length of the forehead. Make your mark, and check to see if that mark is above the curve of the head. If your forehead is large, but still a little flat like mine, the wig head won't accommodate that. You'll have to make a guess at this point if you wish to add more to the forehead first before adding other measurements.
If you decide to add to that, take some tissue paper and make it into rolled flat pieces. Use tape to help add 'volume' to your forehead to make it a bit more flat. Keep adding this until you get the proper shape of your forehead, and mark not only where the hairline settles, but a vertical marker for the direct center.
Note: This was the first time I had to add to the forehead, and I used flat folded tissue paper to do so. I realized later how HARD it was to push a pin through those tightly compressed layers, so I'd advise working with crumbled tissue paper instead of folding it flat.
Next you're going to want to mark off your ears, so you know where the line of the circumference has to pass, and also where the wig will curve around your ears. Use the measurement to extend it out directly across, and mark it. Then use the height of your ear connections and extend it down, drawing a little mockup ear in it's place for visual reference
Note: The picture has the dot just above the tape, and I realized later I had pulled it too high instead of in a straight line. So I redid it later to set it in place.
Using your measurements and a ruler, begin making strips that will help set the dimensions on your head. There are multiple tape variations depending on the measurement to make a proper strip, since having just a cut piece of tape caused trouble for me. All of them were labeled with their number, and eventually also marked at the half way point for centering.
Start off with #3, putting the tape from the connecting mark of ear to ear and making sure that the center of the hairline match with the center of the tape. This is a good way to test if your forehead was settled at the right length from the head, giving a 'headband' like shape. Use some excess thinner tape to connect the bottom to the head.
First set #1 tape over forehead with the middle parts aligned. Mark the back of the head with a center line as reference, and bring them around to hold them temporarily on the line with both pieces meeting end to end. You may want to use a small piece to hold them together.
Add #2 to the top section as well to where the hairline meets, and extend it down to lay over the connecting point of #1 and flush them at the bottom. Take #6 and lay it with center marks matching over that connecting point at the bottom, ensuring that at least the bottom is as flat as possible.
With that connected, work around #1 from top to bottom, first laying it down the best you can to the ear, and then extending it down the head to attempt to lay it as flat as possible without making an odd shape. You're going to want to make sure that #6 curves or remains as flat as your normal hairline, to ensure you know how far to bring your wig down to cover it. If you're having issues, simply 'pinch' some parts of #1 from the ears to the back of the head. Take a sharpie to follow that line made by the tape along the bottom, and then overlay with another layer of tape to support past that line. If you're having issues seeing your marks, mark the tape again. Also be sure to mark off of #6 where the hairline is extending from the circumference line.
Last bit of tape from #4 and #5 will need to be set in their respected places on the circumference from the eyebrows and the ears, extending about. Make sure they remain center along #2, and move and adjust them to try to get the most round shape. Use a piece of small tape to hold them down to # 2, and add some extra to the bottom of each of them to ensure they don't pop in future steps.
This step is the hardest to explain since the science is mostly guessing and stuffing. Take pieces of tissue paper either in full or in halves and crush them down into balls or oblong shapes. The best places to ensure that the shape is full is to stuff along #2 until it is taut, and then work from the forehead down the back from either side of it. Once you think you've had it full enough use tape to cover up the hole, and then begin to really pressure it tight inside without putting too much tension on the tape, and fill it further.
The reason why you begin to fill the shape before putting any tape over it is because the tissue paper will stick very easily to the tape, making it harder to make the shape. Once it becomes stuck, it is a little harder to move and shift the pieces. Waiting to cover until it's finished makes it easier to fill gaps with little pieces then trying to stuff things into holes where items wont move.
Take your time with this section, and attempt to follow the shape made by your tape so you don't get weird 'lumps' in places. Curing lumps is harder when there are super firm areas, but you can bind them down in place with pressure and tape after you've covered the entire head.
Remember: Crush your paper into balls and do not fold it. Folded tissue paper gives more tense layers to try and stab pins through, making it much harder to hold wigs down firmly. Stabbing through a squished up ball is far, far easier.
Following the markers you've done before, make some clean ones that follow the circumference to your ears, your ears, and then down around the base of your head and your neck. These marks are your guides for attaching your wig later that follow the line of your head and where it should settle over your ears and nape.
Slip your wig over and see how it fits. A good place to start is where the folds go over the markers of the ears, the center of the forehead just past the hairline, and the back of the nape of the neck on either side just past the hairline. This is also a great place to test to see how the fibers are settling out, and see if you need to extend/reduce the elastic in the back without having to put it over your head.
Congrats! You now have your own custom wig head to shape wigs to your proper head size. Now you can do crazy ponytails or set wefts without worrying if the wig will be too taught!