I dont know if this is what you need as i Know you would rather have plans already sketched, But i hope it helps a lil.
http://www.squidoo.com/snakecage
"Should You Build a cage for your Boa or Python?
To build or buy that is the question.
if you have a snake that will not get any longer than 3-4 feet you probably would be just as well off buying a glass reptile cage and outfitting it. If you have a Boa Constrictor or Burmese Python or a larger snake you will eventually need to build your own cage. Boas rarely get over 10 feet but will need a special cage when they get to about eight feet. Burmese and reticulated pythons will need a special cage by the time they become adults. A cage for a Boa does not have to support as much weight as a cage for a python but the cages both must be sturdy and secure so that the snake can not escape.
The cage should be about two thirds as long as the snake is in length and about one quarter as long in width. The cage does not need to be really tall because as these snakes reach lengths of seven feet or more they become more terrestrial and if the climbing branches are not sturdy enough the snake can fall and the branches may fall on him injuring or even worse killing the snake. I prefer a height of 2 to 3 feet. So I believe that for my boa constrictor who will probably remain under 10 feet a cage around 6 feet long 2 feet wide and 2 feet high should be sufficient.
Now we need to consider the materials that we will use. Wood is the easiest to work with but takes the most work to waterproof to prevent rotting and mold. Another choice would be melamine board which is a plastic type of coating on a wooden substrate. Plexiglass or acrylic are good choices as they are waterproof and easy to clean. Glass is easy to clean, waterproof, and mold proof but it does not maintain heat and humidity well. My personal choice is wood with an epoxy type of coating similar to those used on garage floors. You can get the paint in most any color you want. Doors should be made out of a plexiglass that is fairly thick so that the snake can not break it.
Lets discuss some of the other features to consider in building the cage.
Heat - I prefer a ceramic heat emitter overhead with an under cage heater as backup. Spend the extra money and get a quality under cage heater preferably one with a thermostatic control.
Light - While these snakes do not require UVA or UVB lighting it is still a good idea to provide them with a photo-period simulating the area that they are native to.
Humidity - for a healthy snake you must maintain the proper level of humidity that they would have in their native habitat generally for the non-desert species the humidity should be around 70%.
Air flow - snakes do not require a huge amount of airflow to breath. You still need to provide some form of ventilation to keep the humidity at the right level and the air in the cage from becoming stagnant.
Water - this will help in the regulation of the humidity also. The size of the tub that you use for the water is dependent upon the size of the snake. He should be able to easily immerse himself without knocking over the tub or spilling water all over the cage.
Hide - Often most large snakes prefer a shelf on the side of the cage to climb up on. This shelf serves as a hide and should be positioned in the basking area of the cage. An additional hide such as an opaque container, a box or a hollowed out log should be put on the cold side of the cage for the snake to hide in.
Proper guages to monitor temperature and humidity are necessary. If you can afford it get two thermometers with probes. Insert the probes in to the cage one about six inches from the ground in the basking area and another in the cold area about 1 inch from the ground. Then mount the guages on the front or the side of the cage for easy reading. To monitor humidity you will need only one guage and it should be in the middle of the back wall about half way up from the bottom.
If you want to observe your snake in the evening after the normal photo-period use a red light as it does not affect the snake's sense of day and night.
DO not use cedar in any of the construction of the cage.
Before you build the cage be sure you have a spot in the room that the cage will fit and not impede the flow in the room. You want the cage to be away from drafts and preferably not on an outside wall. If it is possible you should be housing the snake in a room that can be locked so that if a snake gets out of the cage it will not be able to roam around the house loose.
The least expensive way to build the cage is to use scrap wood from other projects, the caution here is that the wood can not be pressure treated or treated with some other chemical to kill bugs or stop rot.
The next best method is to obtain fresh cut seconds or shorts from the lumberyard or your local home supply shop.
The look of the cage is dependent upon the location in the house. If the cage is in a separate snake room that company does not visit the cage can be functional without being aesthetically pleasing. If you are placing the cage in a room that everyone enters you probably want to create something that looks like a quality piece of furniture. Appearance is the guiding factor in selecting the type of material you are going to use.
For a furniture quality cage I would suggest using 3/4" cabinet plywood for the top, bottom, sides, and back. Use plexiglass for the front doors. Finish the exterior to match or accent the other furniture in the room.
For a purely utilitarian cage that is relatively inexpensive you can use 3/8" melamine board similar to that used in bathrooms, and 2" X 2" framing materials for the top, bottom, sides, and back. Use plexiglass for the front doors.
No matter what materials you use for the cage you need to determine what you are going to put it on. Some people build a table, some build a cabinet under the cage, others build them into the wall. Whatever your choice is remember that a 20' reticulated python can weigh around 250 lbs or more and the stand must be able to support that weight. The framing under the floor of the cage should be similar to that of a house and about 16" on center.
Another thing to remember is that you do not want to put your snake into the cage immediately after the finish dries because there will be lingering fumes. Allow the cage to air out for about a week before introducing the snake to it.
Make sure that you have sufficient electrical circuitry where you are putting the cage. You will need to have enough power to heat and light the cage. Also, the use of a power strip with dual timers would be great for the lighting as you can set it and practically forget it.
Other considerations are the type of substrate that you are going to use in the cage. Some substrates that come in contact with the wood may facilitate rot, mites, and other bugs you do not want. Newspaper is the least expensive substrate but it is not pretty. Cage carpet is a good alternative but you will need several pieces to cover the bottom. A good alternative is an indoor outdoor carpet cut to fit the inside of the cage and a second piece the same size to use while you are cleaning and drying the other one.
If you like the look of a more natural forest floor you can use eco tec or another natural material made specifically for reptile cages such as shredded aspen or cypress.
Since boas and pythons are carnivorous there is no need to have live plants in the cage. There is nothing wrong with having them as long as they are the same types of plants that they would encounter in their natural environment.
Making the cage secure is one of the most important factors in building a cage. Generally the doors are the least secure part of the cage. Special care must be taken to secure the cage doors so that the snake can not slide them open or push them open. A special lock is made for sliding doors which can be obtained from your local home supply store. For doors that pull open you can use barrel bolts or lock and hasp to secure them."
