Then how are you going to get the cardboard to stay on a certain part of your body without it slipping/falling off?
Updated
This is what we recommend you this time...For the general lines suffering from the harsh winter cold...Heating pad!Moni!挿入冷たいIf you just stick that on your clothes, no other places will be warm except that area.#1196 Yukarin Goes To Comiket #1C85 Edition冷たいBut by sticking it on a piece of cardboard, moving that around will be a cinch....the adhesive heating pad!...which you stick on a piece of cardboard...And you can easily place it on places without pockets, like waist and back....and stick that under your clothes.温かい