Here are the after pictures. I made two pillows so that when the trundle is pulled out the second "mini" person also has a pillow. I used the mattress that came with the bed and just covered it with the new fabric. There is not much room on the trundle at all so I had to use a piece of cardboard and just wrap the fabric around it in order for it to be narrow enough for the drawer to shut.
I hope you liked the pics!