I've been cogitating on it and here goes....
I'll make the dimensions 60 by 30 inches by 15 inches high. Interesting that 60X30 has more square inches of floor than 72X24. If it's more important to you to have length, let 'er rip at 72.
Floor and ceiling are laminated with Melamine coated masonite. Lots of talk about Melamine leaking water, but if it's not scratched, it's fine. I've used it in boa constrictor cages, and it lasts and lasts. I'm leaning towards laminating the interior walls with textured tileboard. The faint texturing eases the clinical look of the cage, but seasoned Dry owners might not want to clean Dry droppings off anything textured; if that be the case, substitute Melamine covered masonite for the interior sides and back. Seal the seams with silicone (it's gonna get wet in there).
The carcass is made of MDF, which is bloody heavy. To reduce the weight, we'll cut out panels from the sheets of MDF on the sides and back, leaving enough to form supports adequate to hold any cages stacked on top. Do the cutouts before laminating the tileboard in place with contact cement.
The front face of the cage is made by cutting large areas out of a solid sheet of MDF, leaving an edge on the bottom as a litter dam, and edges on the sides and top to serve as a face frame. I'd leave a section of MDF in the center of the front as an upright support.
We'll leave enough MDF on the side panels for the ventilation system. Low on one side, we'll cut out a small vent, right through the tileboard, and sandwich some window screen into it between the tileboard and the MDF shell. Only after the screen is in place, will we complete the adhesion of the tileboard to the MDF at that point. On the inside of the cage, we'll add a vent grill to kep the Dry from rubbing its snout against the screen. The vent grills are manufactured by Bainbridge, and can be purchased from their website. http://www.bainbridgemfg.com/cgi-bin/frames.cgi?refer=Specialty
The grills are items 1970, 1971, 1972 under the "specialty" subheading.
On the opposite side of the cage, we'll install the heart of the system, the ventilation.
I have been keeping herps since the Ice Age, and certain species are problematical. In particular, those species that are temperature sensitive, and like a warm spot, but need a cool spot to retreat to. Heat creep, where the warm air from the basking spot eventually warms the non-basking areas of the enclosure, is, IMO, one of the last great agents of ruin in herpetoculture. During a visit to the Arizona-Sonora Desert Museum, Stephane Poulin, who is working with Horned Lizards, pointed out that heat creep was killing his animals until he vented the cage by placing a fan at the heated end to pull warm air out of the cage, and draw cooler room air in through a vent at the opposite end. The result was that the basking area was only warmed by radiant energy from the heat lamp, not by a column of warm air between the heat lamp and the soil. The now happy lizards basked in the cage just as they do outdoors, by absorbing radiant heat, rather than being in a warm air zone.
We are going to give our big, black Drys the same life. At the opposite end from the vent with the cute little grill ($8), we will install the heat source. I'm leaning towards a ceramic ceiling fixture with a 40 watt spot bulb such as goes in a pole lamp, or recessed light. My instinct is to enclose the fixture and bulb in a MDF box with a screen bottom for the light to shine through, but maybe the Drys won't burn themselves on an exposed bulb--other herps don't seem to burn themselves (but then, other herps aren't $1,000 Endangered Species, are they?). However you do it, the result is a heat source on the opposite end from the vent.
Now for the ne plus ultra--the vent fan. (Drumroll). I find that a company called Grainger, which is conveniently located right close to my work, sells something called Axial fans. They are compact, and the feeblest of them will move 19 cubic feet per minute. The volume of the whole cage is under 19 cubic feet, so the fan will turn over the air in the cage once a minute--that ought to do it. The fan gets installed, I'd say, inside the cage in it's own housing, probably a MDF box with a vent grill on the inside surface (to keep the Drys away from the fan blades and any screen used to cover the vent hole), and exhausts to the outside of the cage through a hole in the side of the cage, under the light. The vent fan could also be installed inside the light box, and exhaust through a hole in the sidewall covered by the light box--anything that pulls the heated air out of the cage, leaving only radiant energy for basking and a nice, cool cage to play in. The smaller axial fans from Grainger cost around $25 each, in contrast to what I've found on the Web, where they all seem to cost over $100.
I live in Arizona, and heat is a problem. I'll be using this system when I build my Dry cages, and for Coachwhips too. The room the cages are in is air conditioned, and the snakes will have nice cool retreats if they want them.
Back to Dry cages--the floor drain. We'll install a small drain grill over a PVC elbow of sufficient volume, which drains off to the side of the cage stack. On disinfecting day, we can use the disinfectant of choice, followed by a spray from one of those pressure sprayers that gardeners use, of clean water as a rinse. The water--enough to be inconvenent to mop up with towels--runs out the drain into a bucket, leaving a residue that is easily dried with cloth or paper towels.
The front closure requires thought. Sliding glass panels, such as are offered in commercial cages leave a small gap between them at the middle, where some snakes, especially the valuable ones, like to rub their faces intil they have worn a permanent dent in their muzzle. I'd close my Dry cages with panels that press flat against the face frame and are held in place with small cleats that rotate into position like the closure on a two-and-a-half-gallon aquarium screen cover. The cleats could attach to handles outside the cage by short shafts. The exterior handles can prevented from rotating by installing pins that insert through them into the face frame. That will keep the Drys from opening their own cages by crawling across the cleats on the inside.
Tools needed include a table saw, router with straight cutting bits, laminate trimmer with flush trim bit, and a drill to drill pilot holes for the screws used to join the panels together. Count your fingers before and after cutting the panels--if you have more fingers after cutting than when you started, don't call me....
