I originally was looking for superman comics but couldn't find ones to suit my purse and I found all those covers... So I used them. I did an image search on Google for superman comics.
The dimensions are 7x10 front/7x5 sides/5x10 bottom.
The purse didn't hold up all that well so for the next one I added a stiff plastic placemat from Walmart to the back before I taped it and added some clear thin plastic to the handles to reinforce them. It worked out a lot better.
Good luck : )
Here are some new ones I made...