I made this little tote bag to keep all the potty necessities--so I can grab and go without digging through my bag, and it's cute enough to carry in the bathroom. I have the seat (in a ziploc bag), wipes (in a plastic baggie so they don't dry out as fast), a plastic bag in case of an accident, an extra pair of panties and I need to pick up a little bottle of hand sanitizer.
I measured the seat and got my dimensions from that (my finished bag is about 7"x9")--I squared off the corners too. I also lined the bag with plastic--I took off the stretched out elastic from a shower hat and used the plastic.
Jilli Bean loved carrying the bag into the bathroom in at church today...on one of her many "I gotta potty" trips.