Introduction: Make a Fake Rock Cave/basking Spot for a Reptile Cage.

Picture of Make a Fake Rock Cave/basking Spot for a Reptile Cage.

Here I'll show you how to make a fake rock cave/basking spot for your reptile cage. This is one I've made for my Bearded Dragon, Viggo.

Step 1: Design!

Picture of Design!

This is my original design I made months ago. The design has changed since then, but this illustrates the basic concept of what I wanted to make. A large cave, with a door allowing access to it from the outside, a basking spot above, and a ramp going up. PLAN AHEAD. I can't stress this enough. It will make things much easier for you. I've used Google SketchUp to render this 3-D model. Google SketchUp is a great FREE architectural 3-D design program. I'd consider this (or a similar program which may not be free) to be an essential tool for any craftsman/designer/builder. You can download the program here,
Google SketchUp Download

Step 2: Gather Materials and Tools.

Styrofoam ~ Free (This is trash, you can find it for free. It's used to pack all sorts of things. Try going to the back of an electronics store and asking if they've got any you can save from the landfills. I used a broken styrofoam cooler and some odd packing bits.)
Grout mix ~ $8.98 (I got a carton of Sanded grout mix in HEMP color. The sanded leaves a rougher texture than unsanded. The hemp is a kinda dark gray color that already looks like rock. It gives a nice dark base color and could be used without coloration if you want)
Cement Color ~ $4.96 (I used Terra Cotta. Mixed with the Hemp grout it gave a nice red rock color. This is a liquid color mix. You can also use powdered grout color mix. It's about a buck cheaper, but they were out of the color I wanted.)
Great Stuff Expanding Foam Insulator ~ $5.00 (Trust me, this stuff will make things much easier and is well worth it)
Water ~ (To mix the grout)
Water Based Polycrylic Satin Sealer (Go for Satin, not as shiny as gloss and gives a more natural look. You'll need enough for 3 coats. A small can will probably suffice. )

Knives and hand saws (to cut styrofoam and shape your cave)
Hot Glue Gun and glue sticks (works great for gluing pieces together and it's safe. DO NOT USE SUPERGLUE. Superglue, or other such chemical glues will melt/eat through styrofoam and give of toxic fumes)
Bucket (For mixing grout in)
2 Cheap Bristle Paint brushes (One for applying grout, one for sealer)

Step 3: Start Building!

Picture of Start Building!

The best advice I can give you here is to actually work inside your viv. This helps you make sure it will fit, as well as gives you an idea of proportions. You wouldn't want to accidentally make it too large. Remember to leave some extra room around the edges. You don't want it to be a tight fit now because you still have to grout it.

Start with a real rough cut, just laying things out. Don't glue anything down yet. It also helps if you can draw on the floors and wall of the viv to give yourself reference points for shape. If you don't actually want to mark your floor, lay down some newspaper you can draw on)

Get your basic shape together. Don't worry about leaving holes and don't do any detail carving yet.

Step 4: Glue

Picture of Glue

In order to get everything back the way you have it now, it really helps if you draw marks and lines onto your shape. Trace the outline of a piece onto the piece below it. Trace the bottom footprint onto the bottom of your viv or newspaper. Take off each layer and start gluing things down working from the bottom up (don't glue it to the floor!)

Step 5: Expanding Foam!

Picture of Expanding Foam!

This stuff is truly great. I guess that's why they call it "GREAT STUFF"
Spray it in to fill in all those little holes and gaps.
Use a little more in places you want it to build up.
Leave it to expand and dry overnight.

Step 6: CARVING!

Picture of CARVING!

Pull out your knife and saw and go to town! Time to get creative and let your artistic side show. What you're carving now will be the shape of the final piece. Remember, don't go into too fine detail. The layers of grout will fill in a lot of the small stuff completely. If you want it to show up, cut it deeper!

Step 7: Grout!

Picture of Grout!

Ok now, time make this look like a rock, and not a big chunk of foam.
Mix your grout. Don't mix it all at once. Leftovers will dry out while you're waiting between coats. Try using about 1/4 of your grout per coat. I don't really have a set measurement for water, but you want it to be kinda thin and soupy. It will brush on easier that way. If you're using coloration, this would be the time to mix it in.
Once you've got your soupy grout, start brushing it on.
Make sure you get in all the cracks and crevasses, including the bottom.

Let it dry overnight between coats.

Apply 3 coats! This will ensure everything is covered and it will be nice and strong.

Step 8: Paint!

I didn't paint mine, just used the cement color, but if you're gonna do that, now would be the time. Acrylic works best I hear.

Step 9: Seal It.

This is a very important step. Use a safe, low fume sealer such as Water Based Polycrylic sealer if possible. Shellac also works well but will leave it shiny. I actually ran out of polycrylic so I used shellac inside the cave and on the bottom where it wouldn't be seen.
Use your other brush and apply 3 coats of sealant, once again, making sure to get into every crack and crevasse. Sorry, no pictures here, cause there's not much to see while sealing. Once you've finished, let it air out for a few days, preferably with a fan blowing on it.

Step 10: Enjoy!

Picture of Enjoy!

Well, this step isn't so much for you as it is for your dragon, but hey, you can still sit back and enjoy looking at your handiwork.


CeeCee24 (author)2017-11-18

Nice idea! and all the things are safe for pets I'm assuming?

i have a 2 mos old leopard gecko. i want t make a hiding cavern all along the back of the tank. just so it's one piece. but long enough to have a hiding spot in the hot spot and cool spot. have you done something like that?

bella345 (author)2017-03-23

this is so unique i love the way you made this product

Magnumkai (author)2012-03-21

I like youre design !!

Here's something i made with fome and epoxy...

Medusa1392 (author)Magnumkai2016-08-27

Magnum kids- I have a question for you about your amazing rock installation. I hope you're still active on this site....

Medusa1392 (author)Medusa13922016-08-27

Magnunkai* sorry auto correct

AndrewH112 (author)Magnumkai2015-10-27

Hi Magnumkai , your cages are beautiful do you have a step by step instructions on how to do this ?



roosmum made it! (author)2016-06-27

Thanks for this instructable. Here's mine...

KathyH108 (author)2016-04-25

I made a fake rock but having issues. Its cracking. It took a few weeks to make. I thought it was ok but now that its been in the tank the whole under side is cracking. Im going to have to replace it now but should i be worried about fumes....

Evan_crone-4 (author)2016-01-25

How many gallons is your tank ????

metaljosh2029 (author)2010-01-12

hey man awesome job just wondering if this is water proof i want to make a water fall for my red tail boa out of the same stuff

bschran (author)metaljosh20292015-08-24

making an aztec temple for my redtail it works well, and if you use the clear silicon (pasti dip) it will waterproof it. (using that ontop of the joint compound because i want to seal down the moss im putting on mine so my snake doesnt pull it off :) )

Valeriag87 (author)bschran2015-11-28

Do you have an instruct able on it? Sounds cool! :)

daniggle (author)2015-09-14

would this be hard enough so that the lizard isn't tearing at it and able to eat the pieces?

Badgermushroom (author)2015-02-17

So I already have a bag of unsanded grout at my house. Can I just use that, or should I buy a bag of sanded grout? The unsanded grout is a coco color, and I think it should work, but I dont know....

LivEviL1 (author)2014-12-22

Did your spray foam crack too?

TwoBuy (author)2014-09-24

Stay away from spray paints on this step (or be super sure everything is covered in grout)! When I did it, invisible gaps in the grout allowed some paint to get through and it ate away the styrofoam underneath causing the grout to crack and fall off (not to mention the super toxic fumes it probably made).

natpodu77 (author)2014-01-09

I have a couple questions regarding hydraulic cement;

First,is it hudraulic cement waterproof? I wanted to make a shallow pool for my 3-toed box turtle, so I would need it to hold water. If not I can seal it with a coating of silicone where the water will be sitting.

Second, I am making this roughly 10" wide by 22" long and a sloping 4" to 6"deep ith a section for a filter/waterfall (the deeper part). This means I will have to cover my styrofoam mold with the cement in parts-will the sections of cement bond with each other? I don't think, well I know I can't put cement over the whole thing before it starts to set on me, so I will have to do it in sections if I decide to go this route.

Third, can you color hydraulic cement, and if so how? I don't want to paint it as the whole purpose of using the cement versus grout is the fact that I don't have to seal it with expensive nontoxic sealants or possibly toxic and high VOC acryllic products. Nor do I want to have to wait the 7 hours between the multiple layers of grout, then applying sand texture and painting and sealing and finally applying the silicone. It could take over a month of weekends to get this done that way, plus the extra cure time for the water resistant sealant and the silicone.

I was thinking that with the cement it would take me 2 weekends, one for the molding, and another for the cement. Possibly another day for the silicone and then a week to cure it before my turtle could get to use it.

Thank you for your help with this, I am eager to give it a try.

Bebebrittany (author)2013-07-29

I made something similar to this for my bearded dragon over the weekend and put him on it to test it out and I made the ramp/stairs too steep for him to climb.
He could climb it before I sealed it, but the sealant made the surface too slippery for him to grip onto it.... Any suggestions???

sprinkle sand on top of a wet coat of sealer.. ;)

Roxas54321 (author)2013-07-30

How hot can it get, the basking spot gets around 120

foobear (author)2013-06-11

That is one happy little lizard friend!

Clanotayre (author)2013-01-18

Cool idea! I hope the technique will work in my Green Water Dragon Vivarium...

Magnumkai (author)2012-03-21

If anyone likes my terrarium, I made the rocks from 1 sollid peace of foam , carved everything out and coverd it with epoxy mixed with sand.
Then airbrushed it and and the background is just a nice air-picture covered with glass ...

hZZZ (author)Magnumkai2012-10-01

Like It? I Love It!
If only I could make something like that.

instructa-seal (author)2012-07-27

Did you build the cage also? Its beautiful!
If so, I would really like to see an instructable about it.

instructa-seal (author)2012-07-27

Did you build the cage also? Its beautiful!
If so, I would really like to see an instructable about it.

instructa-seal (author)2012-07-27

Did you build the cage also? Its beautiful!
If so, I would really like to see an instructable about it.

freeza36 (author)2012-03-31

you should probably make sure that the materials used do not contain any potentially harmful chemicals.

Bearded101 (author)2012-03-21


How many inches between the the top of the structure and a 100 watt basking lamp would you recommend for safe basking that won't damage the new build?

Thank you for your help... this seems like a great inexpensive build!

dustintinsley80 (author)2011-11-12

If your using this in a dry set up then it doesn't require any sealant unless you paint it. The matte finish mod podge works really well. I use 3-4 coats of it and on the last coat I sprinkle sand on it to give better traction. Using acrylic craft paints can give a very realistic look.
As far as waterproofing that some people are asking about there are several options, (cement is not waterproof) The best method for small waterfalls, etc is to get a tube of aquarium sealant and rubber gloves, by hand smear the sealant every where that water will be in contact. The other option which is best for really big project is to use a 2 part epoxy paint made for potable water tanks. If your making aquarium decor for your fish a portland cement works best. It just needs to cure in water for 4-6 weeks. If you don't it will cause crazy ph spikes. It's best to cure it in running water like a stream, or if your using a rubbermaid tote change the water no less than weekly. Great Instructable!

jamz1378 (author)2010-01-08

I make all my own backgrounds and hides and have found the best way to do it is with a few layers of cement and to finish just mix up some water based paint with some wood glue (the stuff that dry clear) and some water when dry this seals the hide. if wanting to use in aqauriums you have to remember that the foam will float solve this problem with more cement and you will need to be sealed all over several time to make shore that there are no small bubble holes this will need to be left for at least 4 weeks to dry and curer prier to putting into the tank

HubertF (author)jamz13782010-03-30

i use silicon and attach flat river rocks that ive STERALIZED to the back of the terrariums . this looks good in desert or tropical set ups!

Katelyn92507 (author)HubertF2010-08-05

How did you go about sterilizing rocks? I'm getting a turtle, and was wondering how to make rocks clean enough to put in the tank..

Running them through the dish washer with no detergent works pretty good too.

HubertF (author)Katelyn925072010-11-15

sorry for delay! i just bake them in the oven at 250f for 30-60 min. after i scrub them. i dont use chemicals the heat will kill any bacteria.

Mutantflame (author)2011-10-10

I've made similar things like this in the past, and they work really well!

chemicalvamp (author)2011-10-04

Thanks for a great instructable, Looks remarkably like real sandstone. I need a big supply of foam now :)

meganyoung91 (author)2011-07-19

Absolutely love your enclosure as a whole! Thanks for the awesome instructable!

yamum360 (author)2011-06-04

great instructable! i'm off to the hardware store now

care-bearded-dragons (author)2011-05-11

This is a great instructable. Great article on reptile and bearded dragon caging.

weiblen.c (author)2010-05-23

This is a great instructable.  I am a zookeeper, and this is easily as good or better than some professional work that I have seen.

For everyone wondering about waterproof rock-work for aquaria, you can use hydraulic cement and it will not leach any poisons into your water.  We used it all over the place when we were building aquatic habitats at the zoo, plus at home I keep sensitive aquatic amphibians in tanks with hydraulic cement features and they have suffered no ill effects.

Mix it at a very thick consistency and then you can just use it like modeling clay to build any shape that you want.  You have about five minutes to use it before it hardens, so make it in small batches.  You can build all kinds of shapes this way.

Again, this is the very best how-to I've seen on naturalistic terrarium furniture.  Kudos.  I can tell that you really care about the health and safety of your pet.

smiles816 (author)weiblen.c2010-09-06

My fiance and I are in the process of constructing a cage for our ball python, Mitch. In the cage, we are putting in a waterfall. Because it will continuously have water on it, we decided to go with your suggestion of hydraulic cement. It is made of entirely of styrofoam. Because we already had the shape, and didn't need to sculpt anything, we decided to just coat the waterfall in the cement. So, to coat it, we watered it down (to a soup-like consistency) and painted it on. Now that it dried, we have noticed that when you touch it, it comes off on your fingers like a dust and that you can rub it off the styrofoam. We are wondering if you need to seal it after applying the hydraulic cement or if maybe we just made it too soupy when we applied it, and now it isn't waterproof. Any suggestions? We would really appreciate any!

weiblen.c (author)smiles8162010-09-06

I'm sorry to hear that it didn't work for you.  I would be frustrated.  :)  It sounds like you watered it down to the point where it has no cohesion. There is a chemical reaction that has to take place, in order for it to harden properly. When you mix it in the correct proportions, it is more like the consistency of play dough and it gets HOT if you hold onto it. (The heat is a byproduct of the chemical reaction.)

I posted an Instructable with some step-by-step photos of mixing the cement here:

And here is one where I built some tank features using the cement:

It should definitely not fall apart or come off in flakes if you get it mixed properly.  You can seal the final product if you want to, but you shouldn't have to.

Another thing that can happen if you apply it in a layer that is just too thin, it will crack.  It has to be structurally sound.  You could try creating some sample pieces in a few different thicknesses.  Then you can test the different pieces to see how thick it has to be in order to keep its strength for your project.

smiles816 (author)weiblen.c2010-09-09

Thank you so much! We'll have to let you know how it turns out!

pyro=fire (author)2010-08-13

I have a bearded dragon too love her sooooo much!!!!!!!!!!

radjadd (author)2010-07-03

this is one of my favorite instructables and was the inspiration behind my instructable how to make a log hide for your lizard

TheChemiker (author)2010-06-29

This isn't waterproof, right? Because I want to make one for my chinese water dragon, and there is water in the bottom of his terriarium. I make land by filling in areas with gravel, but the terriarum is always at least damp, because I have to mist it too keep up the humidity. Is it alright if I use it for that?

necajoe (author)2010-06-17

cool what kind of glue did u use

jhd04 (author)2010-06-14

Awesome! And easy too! Large ones of these can sell for up to $100 in a pet store, but this takes about $5 worth of materials. My ball python thanks you.

buchd (author)2009-01-29

Are there special types of paints to use so animals don't get sick? For example, I've heard if you want to do something similar for fish you need to use very specific types of paints. Just curious, because I would love to make stuff like this, but have not been successful finding much info about paints.

About This Instructable




More by RedHandFilms:Make a fake rock cave/basking spot for a reptile cage.
Add instructable to: