I first cut down some medium density upholstery foam to the exact size of the storage chest, I used a 10cm deep foam but you can get different sizes depending on the purpose of your mattress. Then, I used wadding to add loft to the cushion – kind of like a mattress topper! It makes the cushion feel cosy and squidgy.

I simply wrapped the foam in the wadding and used a spray adhesive to stick the wadding to the foam – we picked our spray up from Homebase, but you should be able to find this in DIY and craft stores! Make sure to wrap all sides and then you can cut the wadding to remove any excess. Keep cutting down the wadding to remove excess – you only want one layer of wadding in the end, any overlapping will cause a lumpy mattress!

Use the adhesive spray to glue the wadding to all sides of the foam, if the wadding doesn’t cover all the foam you can use off-cuts to fill in the gaps (I trimmed a large off-cut to fill the last gap on the foam!).

To stop the wadding from separating from the foam over time (especially when you’re squeezing the foam into its fabric cover!), use some stockinette as a cover.

Tie a small knot or pinch and stitch the stockinette at one end, and gently pull down over the mattress.

The inner of the mattress was then completed, so I got started on the cover. I chose the stunning Nouveau Wallpaper fabric from The Chateau to finish off the cushion.

I folded the fabric in half, placing the printed sides together and marked out the size of my foam mattress on the fabric, adding a 1” seam allowance. I then cut the folded piece of fabric to create the two separate top and bottom pieces of fabric for the cushion.

Next, I measured and cut out the two end pieces and two side pieces for my mattress. Not forgetting the additional 1” seam allowance! Placing the correct sides together, I pinned and then stitched the end and side pieces of the fabric to the piece that sits on the top of the cushion. Making sure all the corners match up! Then pin and stitch the bottom piece of fabric to the sides, leaving an opening at one end for the foam to slide into.

Then I inserted the foam into the open end of the fabric cover, and made sure all the corners were turned out neatly. Using upholstery thread, I hand stitched the end opening closed by folding in the edges of the opening and pinning it in place. From the inside of the opening, I pulled the thread and knot through the fabric and did an invisible stitch to seal the opening.

The trick with the invisible stitch is to move directly across the seam, before pulling the needle through the folded fabric. Then when you pull thread tight, the threads are barely noticeable.

Once the opening was closed, I moved on to adding the signature buttons to the French mattress cushion. I used a 12” upholstery needle and threaded my chosen button on with some upholstery thread doubled up. I then marked where I wanted the button to be placed and pushed the needle and thread through the marked spot from the top of the cushion.

When I was confident everything was lined up and in place, I pushed the needle straight through the foam until it poked out of the bottom of the mattress. I pulled the thread ends out of the bottom, and removed the needle.

Then, I threaded a second button onto the loose thread ends on the back of the mattress. To pull the two buttons together (top and bottom) I created slip knot with the end of the threads. First, I tied a loose knot using one of the thread ends, and placed the second thread end through the loose knot. Then, I pulled the two thread ends tight until the button sat the desired depth into the mattress. To secure this in place, I tied several knots with the two ends, and snipped the excess threads.

You can repeat step 10 to add as many buttons as you’d like!

To add a lovely French-style finish, I then added tufting stitches to the outside. I marked along the top edges of the mattress where I wanted these to sit. I spaced mine 1” apart and 2cm above the seam line.

Then, I marked 2cm below the seamline, parallel to the markings above. I spaced these 3cm down from the marks above. I marked all the way along the top and bottom of all seams.

To do the tuft stitches, I used a curved needle – but a straight needle would work just as well! I started by inserting the needle into the lower mark point and pushing it up and out of the top of the mattress, at the parallel marked point. Then, I placed the needle back into the fabric, around 1-2mm away from the mark it came out of, and pulled it out at the bottom, around 2mm from its bottom starting point.

I finished this by tying a loose knot with the first thread end and placing the second thread end through the loose knot. I kept pulling the threads tight into a slip knot until I was happy with the tufted effect. To secure, I tied multiple knots to stop them coming undone. Then, I pulled each of the thread ends in and out of the mattress and trimmed them right down so they stay inside the cushion.

Like a glove…phew!

Once I added some cushions and blankets into the mix, this area became a super cosy reading nook in our bedroom. We love to get comfy on the mattress with a cup of tea and a book…but the kids have claimed it as their new play camp. The best part of these mattresses is that they can be used on the floor or on a bench, I’m planning on making something similar for our garden chairs come summer.