You can have a piece of glass of the appropriate size cut and edged at a glass place. Fasten it to the enclosure with silicone and hinges. You can use the same method to attach a locking mechanism. If you want to install air vents (Which in my personal opinion is not required for most of what we keep anyway) the glass place can cut holes in the glass if you supply the dimensions and have vents to install. Personally, I have the sides of the enclosure a bit higher on the opposite sides to allow for air flow (Not that it is required

) but small enough so that the spider can't get out. 2-3mm in my case. Cutting holes is time consuming and a glass place will probably charge more per hole than the piece of glass itself.
My first attempt.
www.tarantulas.co.za/forum/show-and-tell...-diy-glass-enclosure
Main critique was lack of air vents.
Lesson learned: the lid can drop and break, which it did, and it broke and cost R12 and 10 minutes to replace
This lid I just fastened to the enclosure with silicone, hinges and locking mechanism. It came with the enclosure when I bought it.
www.tarantulas.co.za/forum/tarantula-gen...pe?limit=12&start=24
Currently housing my H incei communal.
Note the gap between the glass and the lid as well. I make all my enclosures like this at the moment and works perfectly for me. No holes, not round vents, just slits.
PS. That little gap is still large enough for baby H incei to escape from. Close with tape when babies are present.
My next project is to convert an existing 60 litre fish tank (1 fish left that needs to die) into an M balfouri communal.
Planning to make a split lid with glass, hinges and locking mechanism in the middle.
My fish tank currently has a perspex lid I had custom made by lunchbox to fit the fish tank, it is perfect, except that it is 7cm too short so that the filter can fit on the site. Might re-use it instead of the split lid, but will see. Perspex scratches easily and over time becomes very dull. Glass stays perfect forever.