All you need is:
1 yd of fleece for the top
1 yd of fleece for the bottom
1 pair of scissors
1 popsicle stick
straight pins - optional
The total cost to make this was under $10.
Step 1: Use popsicle stick to measure where to cut, then cut
You could pin it together if you wanted to or if you don't have a table that is big enough to lay out the fabric flat and you have to do it in sections.
You then use the popsicle stick to measure how wide and how deep to cut - take your scissors and cut on both sides of the stick up to the top of the stick.