How to Make Your Foam Mattress Round (or Any Other Shape)




In this Instructable I'll show you how I made my foam mattress round from one side, and also made the support it had underneath match the mattress. I don't know how to modify a normal bed frame to match a custom mattress, my bed support comes from a construction site's lifting pallets.

My mattress is made from foam, but I suppose similarly and with a little imagination you could modify a mattress that is made from other material too.

I chose a half round shape because that fit my living room/bedroom best but as you'll see you can do any shape you like, the sky's the limit!! :)

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Step 1: Materials and Tools.

I include the instructions on how to modify the lifting pallets, this is of course optional. I strongly recommend some form of entertainment (laptop with films, tv, etc) during the sewing step, it's incredibly boring otherwise. With entertainment you just spend a fun afternoon.


- a foam mattress
- sewing thread to match the colour of the mattress
- lifting pallets for the bed to stand on (optional)


- scissors or small sharp knife
- marker
- big sharp knife
- (optional) knife sharpener (if your knife isn't sharp enough)
- sewing needle
- (optional) jigsaw (to modify the pallets)
- (optional) hammer, screwdriver or drill and wood screws (to modify the pallets)
- (optional) laptop or/and other entertainment (to keep you from getting incredibly bored through the sewing procedure)

Step 2: Preparing the Matress

The mattress cover has three parts. The top fabric, the bottom fabric (they are identical), and a stripe of fabric for the sides. The latter goes around the mattress and is connected with the top and the bottom parts via two thin usually cotton stripes.

Using the scissors or small sharp knife remove carefully the thread that is connecting the small cotton stripe with the top and the middle part of the cover. Repeat for the thin cotton stripe that connects the middle and bottom parts of the cover. You only need to remove this at the place of the mattress you're going to modify.

Pull the fabrics away from the area you want to modify.

Step 3: Shaping the Mattress (and Optionally the Pallets)

Using the marker, draw the shape you want your mattress to have.

Sharpen your knife if necessary and carefully cut the mattress at the desired shape. If the knife is sharp enough, a foam mattress should be cut like butter!

(Optional: lifting pallets:
Using the marker draw the new shape of the mattress on the pallets. Using the jigsaw cut the wood appropriately. Use the screws and drill or hammer and screwdriver to add needed legs to the cut pallets appropriately (this depends on the shape you chose). You will notice that my pallets are already a little modified (using a drill, a jigsaw, and wood screws). There is no need to make an Instructable out of that, I was just in desperate need for some more height on my bed. )

Step 4: Putting the Cover Back On

Cut the top and bottom parts of the mattress cover at the new shape, making sure you leave at least a centimeter extra (better more than less!).

Then prepare your optional entertainment and sew the mattress cover back on by putting the cotton stripe at the edges of the side part and middle part of the mattress and sewing it through (the pictures explain it better - note that I took the sewing pictures after the sewing procedure was finished, sorry).

At all times make sure the side and middle parts of the mattress cover are straight and tight enough. If there's too much fabric on the edges, either trim them or fold them (towards the foam!).

When (after a few optional films) you reach the end, cut the extra fabric from the middle part and sew that together too.

And that's it, your foam mattress is now customised, nobody else has the same one!!

Sweet dreams :)

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    10 Discussions


    6 years ago on Step 4

    Have you ever tried doing something like this with an inner coil spring mattress?

    3 replies

    Reply 6 years ago on Introduction

    Actually i recently had to change my matress and i bought an inner coil spring one. I want to have the same shape so I'll have to modify this one too (i also don't want to lose the lovely bed underneath ;) )
    So yes, I'll make that into an instructable too, and thanks for the motivation to actually do it, i've been postponing it :)


    Reply 6 years ago on Introduction

    Thanks for your reply! I ended up doing my "Harry Potter bed beneath the stairs" to fit in the odd-shaped basement room with a foam mattress after I realized that I'd never be able to flip a spring-based mattress since the shape is sort of like a lazy "L", and flipping it would no longer fit the space since it is so asymmetrical. With a memory-foam based mattress, you can't flip it, see? And now I get to take advantage of the fact.

    It took a new full memory-foam mattress with a zip-style removable cover, a sharp fishing fillet knife, and a lot of playing with autocad online to get the dimensions and weird angles perfect.

    This was a great instructable and really saved my bacon (and potentially my back). Thank you!


    Reply 6 years ago on Step 4

    Thank you that's really nice to hear :)
    Could you maybe put a picture of that crazy L shaped understairs mattress job? I'm curious to see how it turned out. So you meant that you don't *have to* flip a memory foam mattress? i know nothing about those ones, i do know one definitely has to occasionally flip the spring coil ones...


    Reply 6 years ago on Introduction

    depends where you live, every town has their cheap matress provider :P


    9 years ago on Introduction

    I'm going to have to do this!
    ever since i saw a circle matress at IKEA i've been lusting for one.
    thank your this!!!

    1 reply

    9 years ago on Introduction

    You could have gone for heart-shaped... L (great)

    Jacques Terreur

    9 years ago on Step 1

    hey, cool! the tutorial's great! so elaborate that one might get the impression you put the same effort on it than on the actual matress job! ;) the description of the "optional" tools just made me laugh a bit, it's like saying "for this you can use a simple household watch, optional use an atom powered time bending device!" ;) btw: this site really IS awesome!