Basic Box-Type Cage
This type of cage is good for your average
small - to medium - sized snake, such as corns,
kings, rats, garters, and most colubrids commonly
kept as pets. It can be used for venomous snakes also,
because it can be locked with one of those special
"display-case" ratchet locks. It can be made to
almost any dimension that you wish, but for this example
we will make one that is 24" long, 12" deep and 12" tall.
You will need the following materials:
1 piece of 3/8" plywood measuring 2' x 4'
1 piece of 1/4" pegboard measuring 12" x 24"
1-1/2" finishing nails
Carpenter's glue
1 pane of 1/4" glass or plexiglass measuring 11-3/4" x 26"
Sanding sealer, wood stain(optional), and polyurethane
Note: Please read thru entire procedure before cutting, to get an idea of how the pieces will fit together.
You will need the following tools:
Hand saw or circular saw
Hammer
Sandpaper
Router with 1/4" square channel bit and router guide
Paintbrush
OK, let's get started!
First, take your plywood and mark the pieces you are going to cut for the top, bottom, and sides:
Note: Oops! I goofed...what is marked as short/long side pieces above should be reversed...the measurements ARE correct, tho...
Then, cut the pieces and sand the edges smooth.
Next, we will make grooves along what will be the front edges of the cage pieces.
This can be done either with a hand saw or a router, which is much easier.
Mark two lines, 1/4" apart, set back 1/4" from the front edges of the top, bottom, and long side pieces:

Set the router bit to a cutting depth of 1/4" and the router guide so that the bit is positioned 1/4" in from the edge, along those two lines.
Make the cuts all the way across; you should now have three pieces looking something like this:

This groove can be cut with a hand saw and then chiseled out with a flat-bladed screwdriver, but the router is much easier...
ASSEMBLY
Now let's start putting things together. The side pieces will go sandwiched in between the top and bottom pieces, flush with their edges.
Apply a thin bead of carpenter's glue to the bottom edge of the long side piece, and place it on top of the bottom piece, aligning the grooves.
Repeat this for the short piece, which will reach up to the groove in the bottom piece. Use a few books or a buddy to help hold the pieces upright until you glue the top piece on:
Once you glue the top piece on you can start nailing, spacing the nails about every 2 - 4 inches apart.
Start with the top piece, nailing thru it to the side pieces. Once this is done, flip the whole thing over and nail the bottom piece.
Using a damp cloth wipe off any excess glue that oozes out. Then, flip the whole thing over on to its front edge, leaving the back edge up.
Put a small bead of glue along the back edges, put the pegboard in place, and nail it as above wiping off any glue that gets squeezed out.
Once the glue dries(overnite) you can sand the whole thing smooth, stain it if you wish, then apply 3 - 4 coats of sanding sealer, sanding in between each coat when they're dry.
As a last touch, apply 2-3 coats of polyurethane finish over all surfaces, letting dry in between. Once dry, the pre-cut piece of glass or plexiglass is just slid into the groove at one end of the cage, and, PRESTO!
Your cage is finished, except for the inhabitant, some bedding, a hide box, and a bowl of water.