I hate math. But patterns are basically applied geometry, so you can’t avoid a bit of math. The great thing about Iplehouse dolls is that the body sizes are more or less proportionally up- or down-scaled. That makes it possible to do the same with patterns. Most printers offer a custom input field for the printing size scale, that makes it easy.
If you want to scale a pattern for a proportionally similar doll, choose one specific measurement (e.g the waist) of the size you want to sew for. Divide it by the corresponding measurement you have a pattern for.
FID 15 cm, EID 21 cm waist
15 ÷ 21 = 0,714 (71% scaling of your EID pattern should do the trick)
If you need to round the numbers up or down, you’ll want to do a double-check.
Example: 21 ÷ 100 =0,21 (that’s 1%). 0,21 x 71= 14,91 (not quite the 15 cm you want, but you see where you are going)
Of course the formula “I want” divided by “I have” works for upscaling as well. 21 ÷ 15 = 1,4 (scaling to 140%) in this case. That wasn’t so difficult, was it?
Nice little tool for skirt calculation Circle skirt calculator