If your using the t shirt material and super glue , never use poundshop or cheaper superglue... It won't work and is a false economy.
Mask the outside well especially around eye sockets as overspray with interior black will cause problems.
If you can can get green welders lens material then you will find that it works better than the lighting gel. If you cannot source that product then double up on the gel either by folding it in half or use use two sheets.
Hope that helps, and i look forward to seeing the results of your work
Cheers