You will need boxes big enough to have the iPad stand in (I had several sturdy moving boxes given to me.) packing tape, hot glue and mattress foam or sound panels (I also had several of these given to me.) I found brand new mattress foam at Goodwill (They have so much new stuff donated from Target!!!!)
Tape the box together and then measure out your foam sides. Hot glue those in and you are in sound booth business! I added some contact paper I already had to a couple of them. I made eight sound booths with the out of pocket cost to me being $18.99.
Your students just lean in to record their sound. It is crazy how much sound these drown out!