How to Build a Hermit Crab (or other small critter) Cage

Picture of How to Build a Hermit Crab (or other small critter) Cage
This instructable will provide you with the details on how to build a hermit crab cage. If you're not a fan of hermit crabs, you could use it for hamsters. Or lizards. Or mice. Or...well, you get the idea.

The kids decided they wanted to get hermit crabs this summer, but when I saw the price of new cages at the boardwalk sea shell shops, I knew I could make them a larger cage much cheaper.

Kiteman and RedThreadsOfFate added some words of advice on keeping hermit crabs and I think it should be pointed out as well. Hermit crabs require an environment with high humidity (70-80%). Although this mesh cage will not provide that environment, it will serve as temporary housing until a more suitable, permanent home can be found.

If you're interested in learning more about caring for your hermit crabs, take a look at one of the following sites:
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Step 1: Ingredients

Picture of Ingredients
Here's what you'll need to build one like I did. If you want a bigger (or smaller) cage, adjust the size of your dimensions as necessary.

First and foremost, you need a plan. The old adage of "fail to plan, plan to fail" will bite you otherwise. Sketch out your cage from a couple of angles, labeling the pieces that you'll need to build. Be sure to use sizes that are mass produced and easily available at your local lumber yard, otherwise you'll be back at the drawing board.

The measurements below are based on standard size wood stock (but real measurements). For instance, the board that makes up the floor and back was sold as 1" x 12" even though it really measures 3/4" x 11 1/4". I don't know why that is...maybe it's a vast wood industry conspiracy to confuse us or something.

Here's the list of materials (and the dimensions) for the cage I made:


3/8" x 1 1/2" x 18" (4) -- wood trim (2 front, 2 top)
3/8" x 1 1/2" x 12" (2) -- wood trim (2 top sides)
3/8" x 1 1/2" x 10 3/4 (4) -- wood trim (sides)
3/4" x 1 1/2" x 10" (4) -- wood vertical supports
3/4" x 11 1/4" x 18" (2) -- wood floor, back

10" x 18" (2) - wire mesh - top, front
10" x 8 3/4 (2) - wire mesh - sides

2" Hinges (2) (comes w/ screws)
Hook and Eye (1 each)
6" length of chain (need a 3/4" screw)

*the wire mesh was sold in a roll 72" long and 24" wide. This worked out perfectly as I was able to get the four pieces I needed cut with a minimum of waste (see the right part of the plan for a sketch of the four pieces of mesh I would need).


jig saw (a table saw could be used instead)
miter saw
wood glue
staple gun (loaded with 1/4" staples)
sandpaper (fine grit)
wire snips
corner frame clamp (optional, but comes in handy when gluing the top frame)
That is not even big enough for a crab at least a 10 gallon tank which is still small and there is no substrat,meaning the crab could not dig or mild witch is a need for crabs there is also no hiding or climbing or source of heat what I am trying to stay is I think you need to research more of the pet you have because that is not a good environment for a hermit crab
173trav5 months ago
Animal abuser
awire1 year ago

Good blog for helping to make wire mesh boxes with wooden
frames. Such crimped wire mesh boxes are useful for carrying other things also.

kgoodwin31 year ago
No place for a crab to live!

Get at least a 20 gallon fish tank
Thanks for including the humidity tip. :) Saved me the trouble. Pet stores don't even tell people when they buy crabs.
sally3003 years ago
do the hermite crabs get very big
As Kiteman said above, this type of cage isnt suitable for a hermit crab. Hermit crabs need at least 70% humidity (Max 82% humidity) in their environment to breathe. they have modified gills, which wont allow them to breathe completely submerged, but requires them to have high humidity to breathe. they also require warm environments. (between 70-80 degrees Fahrenheit) in order to stay active.

I'm not an expert with other animals, but please try and research a bit more on hermit crabs. they arent throw-away pets and they actually live very long lives when cared for properly, even past thirty years of age!

This may be a good project for other animals, or just to spend the afternoon on, but not for hermit crabs.

for anyone interested in hermit crab care, please look to sites such as

would it be a problem if i asked you to put a disclaimer that this should only be a temporary home until a proper one can be obtained...?
samfelis (author)  RedThreadsofFate5 years ago
Thanks for the detailed information (as well as the specific sites). I'll go ahead and add this to the introductory step.

how many hrmite crabs can you put in there

 It's fine for hermies to travel home in, but not on a 10 hour road trip. In other words, you could bring him to the other side of the state and back (careful not to bang him around) and he'd be a bit shellshocked (no pun intended) but still OK.
Hermit crabs aren't meant to be toted around like dogs.
You can go to to get more information.
sally3003 years ago
is that known as an all time hermite crab habatate or is it just for a few days cause i dont understand it
samfelis (author)  sally3003 years ago
It's probably more suited to a temporary home. I modeled it after the cages I saw at the beach (where the kids got them), but didn't take into consideration that they (the hermies) don't stay in there very long.

That being said, our hermies lived over three years before they died (with a 2-3x a week spritzing in an indoor environment and a weekly bath in the sink), so....YMMV.
Mauigerbil3 years ago
Cool! This could be used to house baby gerbils or mice for awhile before they are too big for it.
crossless5 years ago
 I would use that size only for travelling cage . for hamsters etc..
komecake5 years ago
  I pretty much built the same thing earlier this year, but much taller and I used an old dresser drawer as a base. I was looking for instructions on how to build a base from scratch for when I make an "updated" version, so thanks for the instructions. This looks much cleaner than my cage as well as I wrapped the wire on the outside of the cage because I was afraid of my rats getting cut on the wire. I have a solution for that though.
Kiteman5 years ago
Unless you live in an extremely humid (tropical, in fact), mesh cages are not suitable for hermit crabs - they should be housed in glass or plastic tanks with lids. Apart from that, it's a nice project.
Agreed (on the general subject of "wrong cage type").

For my own two cents, I'd vote for this being renamed, even if it's just to "small animal cage". It's a pretty cool project, but it does smack too much of encouraging people to get special-needs pets before they're ready to take care of them.

That said, looks spiffy for some pets who don't require anything more complicated than open-air environments.
samfelis (author)  Kiteman5 years ago
Thanks for the kudos, as well as the tip on humidity levels. (I had heard that elsewhere, which is why I added "or other small critter" as well as the link on the last step.) So far the hermies love it. The kids spray them every morning and night and give them baths a few times a week (in the kitchen sink, no less!).
try to keep baths to once a week, or better once every two weeks. it can stress them out, especially in a new environment. and hermies love to climb! so make sute they have lots of non-metal toys/objects (metal toys rust, which can harm them). also, as a side note, many tap water and bottled water contains chlorate and chlorine, which can burn the gills of your hermit crab. you'll need some type of water conditioner (like the freshwater aquarium stuff) to make sure your water is safe for them. chlorine will evaporate, but chlorate wont.
samfelis (author)  RedThreadsofFate5 years ago
We do condition the water before we bathe them and the spray bottle water has been conditioned as well. We have fish as well so are well versed in having to condition the water.
fantastic! i hate to think how many poor crabbies have died because someone burned their gills with tap breathing bleach! well, this is a good project, and i think if someone lowered the proportions, and made the mesh smaller, it could also be a bug habitat!
Daethian5 years ago
Thanks for adding the disclaimer about this not being a suitable permanent home. Thanks to the others for linking to us at CSJ! w00t! You could still build a very cool home habitat with plexiglass. I've seen that done numerous times. OR watch Craigslist and yardsales for FREE tanks, doesn't even get cheaper than that.