The ones with the fluorescent tube? I use just standard 8-1/2" x 11" white copy paper and wrap the lamp. Two sheets in landscape orientation end-to-end will cover the entire lamp. Typically 1 or two wraps is all it takes and then just tape it with a few pieces of clear tape. I've done both Metallica and TSPP. TSPP has been this way for 10 years now with no issues.
If it's too bright give it another wrap. Too dark, unwrap a turn.