I'm currently working on a complete guide on how to build snake cages which will be available soon.
However, until it is published, here are some guidelines to help you when building snake cages.
Materials
Snakes can be strong, can spill their water and defecate anywhere they please, so the choice of materials is important.
Plain wood will soon absorb moisture and warp, smell or rot so isn't recommended.
Metal may well rust under these conditions, looking unsightly and serving
as a potential hazard for your snake.
Glass must be used with care so that no sharp edges are present which may damage you or your pet, and that it is securely fitted so breaks cannot occur.
Generally the most suitable materials for those wanting to build snake cages are plastic and water-proofed wood - such as if water-resistant
paint or varnish have been used. These treatments themselves may cause problems though, for example
if a paint contains lead, so much care needs to be taken over the selection and application.
Security
Snakes are professional escape artists and one of the snake cage builders greatest challenges is to ensure a cage is escape proof.
Small gaps, holes, slits and warps in any materials used ot joints can allow your snake to escape, as can loose fitting lids and doors, or any other part of the cage
light enough for your snake to move.
This means light-weight plastic lids that can be pushed off are out, as are sliding doors that can be manoevered by a strong snake.
I have had corn snakes and iguanas escape from home made cages that simply
didn't prevent sliding doors being moved by the reptile in question.
And wrestling a 4 foot, angry iguana back into his cage after he's spent all day sitting on my couch while I'm out at work isn't the sort of task I relish!
Nor is clearing up the mess he's created!
Incidentally, cage locks are available to help prevent this occurence.
Life Support Systems
Most snakes in most parts of the world will need heating.
Many others will require lighting - either because they need it biologically or because
their cage is so dark that without artificial lighting you just don't get a good view of your snake.
Consider how you're going to install these lifesystems before you start building
the cage so you know in advance what goes where and how you're going to control the wires.
Ensuring a decent lip or hood exists at the top of your home made cage helps to hide the lighting tubes themselves, and ensures
that the light shines down into the cage rather than straight out sending you blind any time you try to admire your pet.