The size of the enclosure is all up to you. I built this one for my 4 month old ball python named Marley, I designed it so that he could grow into it and it would still be a large cage for him. Before I built this he was in a 10 gallon tank and he loves this cage. this one is 30" W x 26" D x 10" H.

Dimensions of the cage: The cage can be whatever size you would like it to be, but keep in mind what kind of reptile you have. ball pythons being ground snakes there was no real need for the cage to be very tall. I had plans to build a cage for two baby bearded dragons so they could grow into that one and I figured that a cage 14' high was the best. Included in the bearded dragon cage design would be expanding foam ledges (discussed later). If you would like the cage to fit into a certain space be sure that the cage including the supports can fit in that area.

Materials:
-Table saw (or circular saw)
-Jigsaw with a plexiglass cutting blade, along with a standard wood cutting blade
-drill
-wood screws 1 1/2"
-screws 3/4" and 1"
-pine wood 1"x2" and 1"x3" (comes in 8' and 10' sections at Home depot)
-2"x2" for supports
-Plexiglass .093" thickness
-plywood about 1/4"
-screen clips
-1" hinges
-1 1/2" bolt latch
-Mesh screen (screen door screen) optional
-white pegboard
-hot glue gun
-staple gun
-any stain (your choice I used the small can and was able to stain the entire thing with about 1/4 can left over and i used woodstock stain)
-mold resistant white paint (I used a pint size and it was plenty)
-sand paper 100 grit and 60 grit and maybe 40 up to you
-jitterbug (electric sander)
-clamps
-L square

Step 1: Dimensions and Cut Sheet

The cage I built was designed so that it would fit between the end of the bed and the wall, and worked for the snake.

The pine wood used for this project is extremely smooth and it wont be found in the normal lumber isle at Home Depot it will be somewhere else and it is just simple 1x2 and 1x3 pieces of wood and are fairly cheap

1"x2" Cut Sheet:
Figure your total height and subtract 2". That height will be the height of the vertical frame pieces on all sides there will be 6 of those.
Figure the depth of the cage and multiply that by 2 this will be your top cross piece for the left and right sides.
Figure the width of the cage this will be the length of the top cross piece only on the front

Add all these lengths up and that is how much 1"x2" pine lumber you will need

make sure all the pieces are able to fit on the number of lumber pieces you get

1"x3" Cut Sheet:
Figure the depth of the cage. Now measure the width of the two upright pieces add them together and subtract that number from your depth of the cage. This will be the bottom cross piece on the left and right sides
figure the width of the cage. Subtract the width of both the upright pieces. This will be the bottom cross piece for the front

Plywood:
You will need 2 pieces to fully cover the top and bottom of the cage or you can do a mesh screen top with interior heater such as a light socket screwed to an interior edge with a metal grate over it for protection. In the case of interior heat and light there would only need to be one piece to cover the bottom.
-------------------There will need to be excess plywood for the door frame and supports---------------------

Plexiglass:
Measure the opening on the left and right sides add 1" to the width and height of the opening so the plexiglass with be 1/2" past the opening of the frame. The Plexiglass goes on the inside of the cage
Measure the opening on the front of the cage do not add any extra length or width to it try to get the piece of plexi as close to the size of the opening as possible

Pegboard:
The pegboard will be the entire back side of the cage for ventilation.

Tip: for corn snakes, bearded dragons, and water dragons and general reptiles that enjoy climbing go to a reptile store and look at what enclosures they have for their climbing reptiles in to get an understanding how tall yours should be.

Step 2: Cut and Assemble Part 1

Cut the pine pieces first and clamp them together. Wait to cut the pegboard and plexiglass and the plywood

screw the bottom 1"x3" and the two vertical pieces together first. Use the Square to make sure they are all flush and aligned properly.

Finish off with the screwing on the top cross beam. Repeat for the 2 remaining sides

(Blue lines in picture refer to screw locations.)

Once you have all three sides in place stand them up vertically and clamp them together using the square to make sure they make a 90 degree angle from each other.

The side frames go behind the front frame there is no reason to add screws into the front frame as I did.
Instead take the screws and drill them like the picture below

Step 3: Cut and Assemble Part 2

Measure the openings only on the left and right sides. Add 1" to the height and width of the opening and cut your plexiglass to those dimensions.

Measure the front opening EXACTLY, then cut another piece of plexiglass to those dimensions.

I found that using a variable speed jigsaw with a plexiglass blade (yes they have those it was a plastics cutting blade with very fine teeth) While cutting I went fairly slow and I had the plexiglass sheet clamped down between two pieces of wood so it wouldn't bounce and crack. GO SLOW! faster you go more cracks.

Put all the plexiglass off to the side for now that is the last step

Pegboard:
measure the back opening on and cut a piece of pegboard so it fits into that position and screw it in.

Plywood:
Measure the top and bottom of the cage and cut 2 pieces of plywood to fit there screw only the bottom one on.
The second one is the top and you need to cut 2 holes into it for the lights and heat lamps I used a compass creating 10" circles. I took the diameter of the lamps and added 2 inches which was excessive 1" would have been fine.

Start with 100 grit and do a few passes with it, then go to 60 and finish it off like that. I did this and the plywood was very smooth and splinter less.

DO NOT PUT TOP PLYWOOD ON YET VERY LAST STEP

Another option is to do the interior lighting idea this would require bulb sockets and cord holes in the top of the cage and don't forget to put cages over the lamps. The light cages are sold for wood vision cages and you can buy them I would recommend using some screen door screen and wrap it around the metal cage so your scaly friend doesn't get curios and burn itself accidently

Step 4: Door Assembly

Take your excess plywood and using 3/4"-1" strips make a frame that will fit inside the front opening.

There should two frames built, these two frames will "sandwich" the Plexiglass.

clamp the two frames and the plexiglass together and drill pilot holes, use 3/4" screws. The tip of the screw should not poke out if it does use shorter screws.

Decide which way you want your door to swing if you want it to swing down place the hinges on the bottom and a bolt latch on each side.
If you want it to swing like opening a book (real hassle because the door is so long) place the hinges on left or right and then you only need one bolt latch.

Step 5: Finishing Up

Paint:
Paint the entire interior of the cage white it booth water proofs it and resists mold. 2 solid layers is ideal. Don't forget to paint the underside of the top piece of plywood

Stain:
Stain the exterior and all the exposed ledges don't forget the door frame.

Plexiglass:
clamp the plexiglass down onto the interior of the cage so it is about 1/2" over the opening and mark where it is. Drill the pilot holes for the screen clips do not tighten them down all the way I used 3 for the long side and 2 for the vertical edge. put the plexiglass down and tighten them all down and hot glue around the edge of the plexiglass.

Screen Clips:
I used screen clips that were smaller than the actual plexiglass. The plexiglass was .093" and the screen clips were .08". It allowed me to tighten them down a lot so the plexiglass couldn't move.

Mesh:
Measure the pegboard from the interior of the cage and add 1" to all the sides and cut out a section of screen using those dimensions and staple them to the pegboard making sure some is stapled to the pine and plywood sections pull just a little over the top edge of the pegboard for when you screw the top plywood piece on.

cut 2 large squares to cover the holes on the top and staple them down.

Hot glue:
I hot glued all the edges of the cage so that no water escapes if any builds up along with the edges of the mesh and around the sides of the plexiglass.

Door hardware:
Place the door hardware on according to how you want the door to swing

Step 6: Last Few Steps

Stand:
If you decided to have a stand for it drill 4 pilot holes into the base of the cage in each corner.
Cut 4 pieces of plywood about 6"x6" and attach 2"x2" pieces to the center of each one.
place the cage on its side and attach the legs.

Top:
Set it down on the legs and screw on the top piece of plywood.

Step 7: Optional: Ledges

Get expanding foam and some reptile safe sand

place a piece of wood or cardboard on the ground and you can build up a ledge using the expanding foam and as its drying throw sand onto it so it becomes realistic. For heavier pets make sure there is a support in the ledge i.e a piece of wood with foam around it for effects or the ledge can have a pillar underneath it made out of the foam itself very cool stuff

I did not do the ledges in the picture it is just grabbed off the internet.