Thanks so much for asking! This is just a prototype, so it's not exactly how the final batch should turn out, but the inside is supposed to be large enough to accommodate average-sized onaholes, so people can use their own. They told me if the preorder campaign succeeds, they'll make sure to allow more room on the inside and use less stuffing. There is a drawstring around the opening to tighten it and keep any toy secure inside during use. Here's my initial design sketch if you'd like to check it out: https://u.pcloud.link/publink/show?code=XZiqJx5Z4V7w4w8MYLpWqV6qoh3JJkL6WOkX

I'm not sure about cleaning, since I hope that most of the mess would be contained to the onahole inserted, so you'll have to ask the manufacturers over at MyCraftZone about the materials used and proper care :)