I used a rubbermaid tote. I cut the middle of the lid out so that it was just a frame. I stuffed the tote with old carpet and whatever else I had on hand. I put cardboard over this and then snapped the lid in place over the cardboard. I print out free targets from the internet and tape them to the cardboard.

It has held up well. I just have to change the cardboard out once in a while. This might make me incredibly cheap, but I would rather put money into the bow.