If you enjoy climbing but not going very high and enjoy challenging problems but hate ropes, then bouldering is for you! Since there are no ropes for belay, your only safety is a nice mat to land on when you slip off or reach the summit and top-out.

A bouldering mat is basically a firm crash mat that you carry around with you to outdoor climbing locations and your climbing buddy places it underneath you as you climb. The large mats can cost £150+ which is more than I wanted to spend to save myself from broken bones and sprained ankles. I have access to foams and a sewing machine so made my own and you can too.

Please feel free to throw a vote my way if you like this!

Step 1: Tools and Materials

A good sewing machine
Scissors
Tape measure
Straight edge
Scalpel / long craft knife
Biro / Marker pen

3.5 x 1.5m of waterproof, hardwearing material. I used PVC coated nylon. A good tarp sheet could work too.
2 x 1.5 x 1.0m of high density closed-cell polyethylene foam. 18mm thick. Camping mats are an easy source of this.
1.5 x 1.0m of low density upholstery foam. 50mm thick. There’s a truck in the market that sells foam cut to size. Sofa cushions are full of this stuff if you’re not buying it.
25mm nylon webbing
50mm nylon webbing
2 x 25mm bullet clips
2 x 50mm strap sliders
1.5m of 25mm wide Velcro
Lots of heavy duty thread.

Step 2: “I Cut This Piece Twice and It’s Still Too Short”

The finished mat will be about 1.5m long, 1.0m wide and 86mm thick when laid out and 1.0m x 0.75m x 0.172m folded in half. Based on an amalgamation of designs I had seen, it will fold in half, have removable foam inserts, carry handles for suitcase style and backpack and clips for closure.

The cover is basically two large pieces to make a cuboid; one is the inner surface and closure flap and the other piece is the other five sides. The cover is split into two pockets 1.0m x 0.75m that open along the 0.75m side with Velcro which hold the foam.

The two pieces are 1182mm x 1864mm (Piece A) and 1096mm x 1520mm (Piece B) in size, both rectangular. This covers all sides and allows 10mm seam allowance on all the joins. Using only two pieces limits the number seams to sew but also improves the waterproof qualities by having solid fabric along the underside of the mat that could end up in a puddle or on muddy ground.

Step 3: All the Fixings Please!

Before sewing the pieces together, you’ll want to attach all the fixings first.

I threaded my machine with extra-strong thread for very solid seams. The thread is thicker so adjust the tension of the machine and the bobbin case to match. I’m also using a 16/100 needle for extra oomph. Spray silicone spray lubricant onto the thread, material and bed of the machine to help ease it through and prevent skipping stitches.

Cut two pieces of 25mm nylon webbing at 225mm and singe the ends with a lighter to seal the ends. Sew them on the 1182mm edges of Piece A centred along that edge. These will form the suitcase handles on the outside. I sewed the ends down in a 20mm square to thoroughly secure the handle; you don’t want it tearing off as you pull the mat along.

Cut four 250mm lengths of 25mm webbing to attach the bullet clips and seal the ends with a lighter. Sew one piece permanently to one side of the clip and leave the other end loose so you can tighten the straps as needed. Sew them to the short sides of Piece A so they keep the mat closed when folded in half. Sew down 100mm of each strap to keep them secure.

For the backpack straps, take a look at an existing backpack to get the concept of what you’re trying to achieve. Cut one long piece of 50mm webbing around 1500mm and seal the ends. Sew the strap to the centre bar of the sliders. Half the strap and fold 90 degrees 100mm out from the centre so you have a gap of 200mm between two downward pieces 650mm long. The 200mm section wants to be sewn to Piece A so that it is centred on the mat when folded in half and about 600mm up from the bottom of the mat. Sew all along the horizontal section to make a secure fixing. Cut two 400mm pieces of 50mm webbing and seal the ends. Sew the ends to the underside of the mat bottom where the top straps lie the full 86mm thickness so you have 314mm of webbing hanging up to thread through the sliders on the top straps.

Velcro will close the flaps formed on the top for the two pockets. Cut two lengths of soft Velcro 750mm long and sew them in position along the top edge on the wrong side of Piece A. Cut two lengths of rough Velcro 750mm long and sew them in position 51mm down from the top edge of Piece B. When the two pieces are sewn together, the Velcro should line up to close the top edge perfectly.

Step 4: So, a Needle Pulling Thread

With all the hardware sewn on, we can start sewing the cover. Starting along the bottom edge of Piece A, fold the corners in along the diagonal from the corner to 96mm in from each side. This forms one of the corner seams. Sew a line perpendicular to the edge and continue off the material like you’re sewing a dart. Turn this seam out to form the first corner. Do this to the other corner of Piece A.

You want two of these corners in the middle of the bottom edge as well. Cut up the centre line 96mm from the bottom and make the same corners as before, treating the cut line as the edge. You should end up with four corners that form the bottom edges of the two pockets. Now you can sew Piece A and B together.

Line the two pieces up so the edges are level and sew all around the three sides with a 10mm seam allowance, leaving the Velcro edge open. When you come to the centre of Piece A, try and lay the piece flat and consistent along Piece B to get neat seams. One more line to go!

With the two pieces together now, turn the bag inside out so all the fittings are on the outside now and make a crease along the centre line of both pieces which will become the fold for the mat. Carefully feed this through the machine and sew from top to bottom along this crease to form the two pockets. This is all the sewing done, great job!

Step 5: Foam Party, Wooo!

Take the pieces of foam and cut them to size, 1000mm x 750mm. Use a marker pen and a ruler to mark out the rectangles on the foams and cut them out with a scalpel or craft knife. Cut in a continuous motion, not a sawing motion to get a clean cut. With all the trimming done, you should have four pieces of the 18mm dense foam and two pieces of 50mm soft foam, all the same size.

Sandwich the one sheet of soft foam between two sheets of dense foam and slide the whole chunk into the pockets of the cover. Repeat for the other pocket, seal it up with the Velcro and you have your completed bouldering mat! If all the sewing was neat and correct, the foam should be snug and tight in the cover.

Step 6: It's Time to Party

It should fold in half nicely and open out to reveal a completely flat, seamless surface 1500mm x 1000mm which should be plenty of landing space from a tricky overhang. The clips will hold the two halves closed in transit and you can also stuff a cheap door mat or jacket in the gap for cleaning your shoes off or looking cool by the wall. The side handles are also great for pulling the mat along whilst you spot fellow climbers. For very high dismounts, keep the mat folded so there are all six layers of foam to cushion the impact. You can rearrange the foam layers if you want a softer or firmer landing depending on terrain.

Overall, I consider this project to be a great success and much cheaper than commercial mats for very similar specs. The only change I would make on another one is to make it small enough to fit in the boot of a regular hatchback car. American cars have huge trunks, so this isn’t an issue but it did not fit in a Renault Clio, Suzuki Swift, Mazda 2 or Vauxhall Astra and had to sit in the back seat. Being able to take the foam out does make for more compact packing. After taking it on a bouldering expedition, it worked just as expected, no-one broke any limbs and we all drank lemonade.