Why bother with buying bath sponges, when you can easily create your own?
Using 3Dsimo Mini and hot wire cutting attachment, you can make your own bath sponges within minutes.

All I had to do was prepare my attachment by tightening the wire between the both ends of the attachment.

Next, I have turned on the continuous mode on my 3Dsimo Mini and start cutting out new, fun sponges out of foam block or sheet.