Just simple Sally beauty supply 40 volume. Any lower and it will still work, just slower, any higher and you'll burn it. The white stuff, not the clear (I haven't heard of anyone using the clear, might work still though?)
Doing a session now inside in the heat with sun shining through the window and a UV lamp on it. Definitely getting brighter.
I don't typically recommend using cling film. I've had awful results using it. It's not worth the risk. Many others think the same. If the item fits in a ziplock bag though, just use that. A compact Mac is a little too big.