The bag started off as one of my fleece liners for my hedgehog's cage. The solid colors are anti-pill fleece so they don't wear as visibly. The base is a 7" x 9" (17.8 x 22.9 cm) rectangle and the sides are 7.75" (19.7 cm) tall and double layered to help minimize the amount of heat that escapes while staying breathable. At the top there's a drawstring to pull the bag closed, but leaves a hole big enough to allow circulation (as seen to the left)

 On the inside are long strips sewn to the sides near the top so that they hang down, but are easily swept out of the way if you need to find or pick up your little hedgie. There are also strips attached to the bottom so that when the sides are pulled back they still have the ability to hide if they get scared.

 The bottom is also double layered with a flap open to the outside. This provides for a removable plexiglass sheet (not shown) that supports the carrier so that the hedgehog doesn't slip to the middle when it's picked up. I also made a plastic sheet with a rice pouch attached so that on a cold day it can be microwaved  and slid into the bottom pouch as shown. This way the hedgehog can get as close or far away from it as they need depending on how cold they get. Both are removable so that you can wash the fabric portion separately.