Introduction: 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:

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)

Step 2: Cut/sand the Wood

Picture of Cut/sand the Wood

Measure and mark the pieces you'll need before making your cuts. For the front and side trim pieces, as well as the vertical supports, you simply need to make a horizontal cut.

For the top frame pieces, however, you'll need to make angle cuts. Since the frame will be a rectangle, set your miter saw to cut 45 degree angles (or 135 degrees). Place all four boards in a stack and make a single angled cut on one end of the stack. (See the graphics below.) This will ensure that that the angles are complementary once you're done cutting. (Of course since all the cuts should be 45 degrees, they should be complementary by default, but just in case your miter saw isn't 100% accurate, making the cuts this way will ensure they'll fit together nicely). This will make them fit much better than if you cut each one separately.

After the first cut, rotate the wood and cut the opposite end from the other side of the blade (e.g., if the the majority of the wood was to the left of the blade for the first cut, place the majority of the wood to the right side of the blade for the second cut). Once you make the second cut, you'll have four pieces of wood that will fit together nicely.

After you've got all your pieces cut to length, use fine grit sand paper on the ends to remove any loose bits. Also, you might want to go over the rest of the wood with the fine grit sand paper as well to make it nice and smooth. This will help later when you paint your cage. (Sanding isn't required, but helps make a better looking end result.)

Cut the floor and back panel to length using your miter or table saw. If you're using a jig saw, it's recommended that you clamp a straight edge to the wood so that the jig saw has something to use as a guide. (See the picture below to see what I'm talking about here.) It's very hard to cut a straight line freehand and having the edge removes the need from having to straighten it later with a rasp and sandpaper.

Don't forget your safety goggles and hearing protection around power tools!

Step 3: Glue the Wood

Picture of Glue the Wood

Once all the pieces have been cut, it's time to glue them together.

Lay a bead of glue along the back of the floorboard and press it against the piece of wood making up the back panel. If you have large enough clamps, go ahead and clamp the two pieces of wood together to get a solid seal. You should now have an L that, once dry, will stand on it's own.

Before it dries all the way, you'll want to glue the four supports on. Glue the back two supports 3/8" from the side of the floorboard and abut against the back panel. Glue the two front supports 3/8" from the side and 3/8" from the front of the floorboard. (The supports are offset by the thickness of the framing strips.)

Before the back, floor and supports dry, glue the framing strips (so that you can ensure the framing strips are flush with the floor and back -- not required but it gives a neater finished appearance). Glue the bottom strips first (in order to get a better bond, clamp the strips to the supports using your clamp of choice). Once the bottom strips are dry, repeat the process with the top strips. I found that by turning the cage over, the strips wouldn't slide down the supports.

For the top frame, you can either glue the pieces and hope for a tight seal or use a corner frame clamp (see picture). The downside of using a corner clamp is you need to wait for the pieces to dry before moving on to the next one. The upside is that you're going to get a better bond and a stronger overall frame.

While you could strengthen the bonds by adding some wood screws to the joints, I don't think it's necessary for hermit crabs. They're not going to be rocking the cage like other critters might.

Step 4: Paint the Cage

Picture of Paint the Cage

Now that the glue has dried, it's time to paint the cage. Pick out a color scheme that you think your critters will enjoy. Or that you (or your kids) will enjoy. Or both. You can either use spray paint or a paint brush, although using spray paint will result in a smoother finish.

Prior to painting the cage, you should prime the wood so that it won't soak up the paint and require you to put on more than two coats.

Once the primer is dry, follow the instructions on the paint and paint the cage.

After the paint has dried, you may want to add a coat of shellac to seal the paint from any moisture sources you'll be adding to the cage (unless you're using high-gloss paint, which should be somewhat moisture resistant already).

The picture attached to this step is from after the cage is completely done. You can see the kids decided to have fun with the colors. Go for something fun!

Step 5: Cut/install Wire Mesh

Picture of Cut/install Wire Mesh

After you've finished painting the cage, it's time to cut and install the wire mesh.

Measure the opening on the left side of the cage (or the right side, it doesn't matter) from top to bottom and front to back. If you followed my plan, it will be about 8" x 10" or so. You'll bend the wire so that you can staple it against the vertical supports, so make sure you add another 1/4" - 1/2" on either side (so that it's ~9" x 10"). (The wire mesh in the materials list is sized correctly. If you're following this plan, simply cut them to size as listed in Step 1.)

Bend the mesh along the long side so that there is a row of squares making up the right angle.

This can be easily done if you place the wire mesh under a board (except for the edge to be bent) and then fold the wire up (using your hands -- the wire is pretty malleable).

Do the same for the opposite side and then slide the mesh, with the bent portions touching each of the vertical supports so that the wire completely covers the opening. You may need to adjust it a little if the bend was too big (or too small).

Staple the mesh into place using your staple gun (remember eye protection!).

Repeat this process for the front and opposite side.

For the top frame, simply measure the interior of the frame, add 1/2" to the length and width and cut the mesh to size. Staple in place and you're ready to go. No bending is required for the top mesh.

The pictures below are from the finished cage. It should give you an idea about what I mean above by bending and stapling the wire mesh.

I found it easier to deal with the wire mesh when it was cut as close as possible to each square (e.g., there were no "orphan" wires sticking out). This also makes for a cleaner finished product.

Step 6: Add the Hardware

Picture of Add the Hardware

Once the mesh has been installed, you're ready to add the hardware. In this case it's a pair of hinges, a hook and eye latch and a chain (to keep the top from opening too far).

For the hinges, it's important that you add them so that they'll support the frame evenly. I found it easier to put one side of the hinges on the cage first and then screw the frame onto the other side. You may have other ways of doing this, but, regardless of which way you do it, be sure to drill pilot holes first! If you don't you run the risk of splitting the wood (especially on the top frame, which in my case was only 3/8" inch thick).

For the hook and eye, position the eye in the center of the front of the top trim and the hook in the center of the front of the front of the top frame. (See picture below for specific location.) After drilling pilot holes, screw both the hook and eye into their appropriate places. You may need to bend the hook a bit to make the connection a little tighter.

Finally, attach the chain so that the lid will open to 120 degrees or so. This will allow you to open the cage and reach into it without having to use one hand to keep the lid open. Using a screw that's a tad bit shorter than the vertical support is deep (~3/4"), attach one end of the chain into one of the vertical supports and connect the other end to the wire mesh on the lid.

Step 7: Add the Critters and Decorate As Necessary

Picture of Add the Critters and Decorate As Necessary

Now that you've finished your cage, it's time to add your critters and decorate their home to your heart's desire.

Watch out for the claws on the hermit crabs, though, they've been known to pinch!

For more information on keeping hermit crabs as pets, check out some of these online resources.


SciddlyB (author)2016-10-09

This is extremely incorrect, no humidity, substrate or warmth. Next time why dont you research something before spewing misinformation leading to a creatures death.

EvanR11 (author)2016-08-04

I can't stop looking at how ugly that boy is

EvanR11 (author)2016-08-04

The poor crab dose not have anything it needs like heater humidifier hiding place bending ISO extra shells and has to stay with two dorks all the time I Realy feel bad for the poor guy! Your torchoring the little guy! TRY HARDER!

sally300 (author)2011-09-12

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)sally3002011-09-13

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.

Mine is going on seven years with me--and had lived with the previous owner for seven years.

In order to be nice to hermit crabs and their caretakers, this posting should be removed, because if someone puts them in this cage, they'll die.

There is no way to have a cage with the required 70% humidity The enclosure must be sealed (like an aquarium with a lid) and have plenty of moisture and moisture-retaining substances (the substrate, pools of treated water both non-salt & salt, sponges that have been dipped in water).

WingraMax (author)2015-10-19

This is animal abuse. This is a misleading intractable and should be taken down! This intractable should be called "How To Kill Your Pet Hermit Crab"

WingraMax (author)WingraMax2015-10-19

Please remove this instructable

Ashton c (author)2015-10-09

Also a cage is extremely bad for them they can get there legs caught. . And that means they're legs fall ot

jmeyer11 (author)2015-08-09

I would have to agree with isabella.mikolainis. Hermit crabs have modified gills, which means that they breathe air, but the air they breathe needs to be humid and moist. Hermit crabs need to be enclosed in an aquarium, with deep substrate and high humidity.

Colin McLain (author)2015-05-24

What kind of hermit crab is that? Its huge!

isabella.mikolainis (author)2014-11-22

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

173trav (author)2014-10-05

Animal abuser

awire (author)2014-01-23

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

kgoodwin3 (author)2013-12-27

No place for a crab to live!

Get at least a 20 gallon fish tank

msminnamouse (author)2013-08-30

Thanks for including the humidity tip. :) Saved me the trouble. Pet stores don't even tell people when they buy crabs.

sally300 (author)2011-09-14

do the hermite crabs get very big

RedThreadsofFate (author)2009-08-20

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...?

Thanks for the detailed information (as well as the specific sites). I'll go ahead and add this to the introductory step.

sally300 (author)samfelis2011-09-14

how many hrmite crabs can you put in there

crazydaizy (author)samfelis2010-03-24

 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.

Mauigerbil (author)2011-08-18

Cool! This could be used to house baby gerbils or mice for awhile before they are too big for it.

crossless (author)2009-11-30

 I would use that size only for travelling cage . for hamsters etc..

komecake (author)2009-10-22

  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.

Kiteman (author)2009-08-20

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.

Wolfbird (author)Kiteman2009-10-08

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)Kiteman2009-08-20

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.

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!

Daethian (author)2009-08-26

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.

About This Instructable




More by samfelis:How to Make an American FlagHow to Build a Hermit Crab (or other small critter) CageSingle Wheeled Bike Trailer
Add instructable to: