There are a lot of articles out there which are more detailed than this, but here are some general guidelines and processes that work for me.
Standard terrariums are typically constructed with 1/4 glass. Â For anything with dimensions smaller than approximately 16″ LxW 3/16 inch glass works just fine. You can do slightly thinner for larger terrariums, but the measurements are made enormously easier using the 1/4. Â The following are instructions to make a very simple terrarium with no drilling or elaborate ventilation.
Technique and Materials
-GE 100% Clear silicone without any additives for mildew resistant. It comes in a clear bottle with a blue label.
-get a decent cauking gun!
-make sure the silicone line you are applying is thick enough to thoroughly cover the glass that is going to be glued. You can always trim off excess later.
-hold the gun a few inches from the glass and drag a line across the pane of glass slowly. Don’t ever touch the tip to the glass as it will be super messy and give you air bubbles in the seal.
-Clean the surfaces you will be glueing together with mineral spirits before making anything permanent. Let it dry (takes less than a minute).
-you want at least one angle clamp. Play with it for a little while using two pieces of glass to see how it works and how tight you want the clamps to be. There are a lot of youtube videos about how to use them, but basicallly you do a trial run with dry glass and work out where on the glass the angle clamp will fall so that you can make a good right angle, and then you loosen the clamp so it is only attached to one of the pieces of glass. You silicone where you need, then you very carefully ease the second piece of glass into the correct position. If you don’t prep the glass in this way, it is tremendously difficult to get the seal aligned, and the silicone will smudge as you try to work it into the correct position.
MeasurementsÂ
The terrarium being constructed has dimensions of 24.5x18x19. Â Below are the pieces of glass used to make it. Â The front door I measure at the end as the channel takes up a small amount of vertical space, and its easy to make a measurement by hand once everything else is put together. Â This is all with 1/4 glass.
bottom: 24.5×18
back: 24.5×19.3/8
sides(2): 17.5×19.3/8
top back: 24.5×10.5
top front: 24.5×2.75
General chronology,
-the first two pieces you attach are the back to the bottom. Â The back goes on top of the bottom. You have to put them on their sides as pictured below.
-the next pieces you can attach are the sides. Â If you have two angle clamps you can do them together, or just wait a day and do them separately. These pieces go in front of the back piece and on top of the bottom piece.
-next you can do the front ‘lip’ or substrate barrier. Â This goes on top of the bottom piece. You can lie the terrarium on it’s back now, so the lip is facing the ceiling. Â It might seal better this way.
-The rest is really easy from here, you just have the top. Â In this case, two pieces of glass were used and a 4″ gap was left between them for a future aluminium screen vent to be put in. Â The terrarium can be put upright and books can be used to ensure that the top pieces are sealed well.
The Door MechanismÂ
-There are many ways to design the door, the terrarium below is very simple and has a clear H channel installed which allows the entire front piece of glass to be removed.  I don’t silicone it as it grips the bottom piece of glass nicely, and then can be removed for cleaning.  Something to keep in mind is that H channels vary, some are tapered so they grip the glass, and others are much wider (Sherman track) and meant to sit on a narrow platform of glass.  I get mine from TAP plastics which stocks a large range of acrylic and plastic products.  It is a slightly tapered extruded acrylic bar designed to hold 1/8 glass. There is also an option for 1/4 inch glass that is not tapered, that looks like it would work if siliconed.  That one is made of butyrate which is a material that stands up to terrarium use wonderfully, and is very easy to cut and work with.  Other options are available for different color track, TAP only stocks clear channel.
The second part to this design is a L channel to keep the front glass in place.  It is cut to the length of the terrarium, and taped to the top in two ‘hinges’ on either side. The duct tape has held up wonderfully for two years and shows no signs of loosing it’s stick.  Maybe one day it will give, but the second piece will offer a safety.
Aluminium window screen vent
If you have ever made a windowscreen for a door, this is exactly the same process. You have 4 corner pieces, the framing(that you cut to size), spline, and screen. Â A spline roller really helps fix the screen in place and is only a few dollars. Â The screen you use can be either stainless steel mesh or no-see-um mesh. Â The no-see-um is tremendously easier to use, cheaper, and very durable. Â The stainless steel mesh is also very durable and supposidly allows more UVB to pass through.
Depending on the species you are keeping, and your misting schedule, you want to make the vent larger or smaller. Â I usually err on the larger side and get a piece of glass cut to the size of the vent, and move it around to manipulate humidity. Â Typically you want to aim for anywhere between 2″ and 6″ of vent. For dart frogs I usually do 2-4″ and for treefrogs I usually do 4-6″.
Cost
The cost of building your own terrarium is inexpensive when compared to commercially available terrariums or custom build terrariums (especially if you factor in shipping). Â The total cost for a terrarium of roughly 24x18x24 is about $110-140 in glass, $5 for silicone (good for up to two tanks this size), and a few dollars for H channel (roughly $1.25/foot) and L channel (roughly $1 per foot). Â The aluminium vent is about $4. So, anywhere from about $125-145 for a 45 gallon terrarium.
Below are two terrariums with the TAP door design,
and another with a different top, for frogs that are too jumpy to have a fully removable piece of glass. This top door just slides forward, allowing food to be put in through a small opening.
