You can always try make up sponges too (brand new of course and from an unopened pack, not one laying around gathering dust!). You can get wedge shaped ones or flatter foam types and cut them to shape. They don't come with anything to pull them out and you should only use them if you are confident that you can remove them (as they can be a little fiddly to remove). Wash hands and put some lube on the sponge and then inside you after you have inserted them. I'm not sure about leaving them in all day or to see multiple clients over a long period but for a 1 hour booking if you excuse yourself to quickly insert it (literally just before you do anything), then it should be fine in an emergency.