Some people with autism (or an Autistic Spectrum Disorder to be precise) find that sleeping under a weighted blanket soothes them and helps them sleep. They can also be used for comfort as a lap blanket or even just a throw around the shoulders.

Our middle child picked up a bag full of change (don't ask - long story) and sat with it on his lap. As he's being investigated for Aspergers, we figured out that he might benefit from a proper weighted blanket.

The problem is that they need to be made to measure. The weight is worked out as a percentage of the user's bodyweight and the dimensions need to be just right. A quick trawl of the internet turns up that the weight should be between 5% and 10% of user's weight, plus one pound. The size needs to be just long enough to cover the person, and the same width as the bed. Somewhat obviously (although I didn't think of it until I read it) if it's wider, then it'll slither off the bed in the night.

Understandably, they are expensive and take a while to arrive. As I have a new sewing machine and had just been on a course to learn how to use it, I saw my chance! I took photos as I went and this was my first one (the other two boys and Mum all like them!) I'll explain the pitfalls as I go along.

Step 1: Gather Your Materials

I spent some time browsing fabric shops. I was looking for something cheap to experiment with when I came across this camouflage single duvet set. I liked the idea of having some of the sewing done for me and also it's much easier to sell stuff to the boys with camouflage patterning!

When there's some maths to be done, the best thing for me is the back of an envelope. I worked out that middle child would need between 4.25 and 7.5 pounds of beads.

I got some beads from Ebay. Search for poly beads. I bought a huge amount as I knew I'd be making several blankets and negotiated a cheap deal with them.

Step 2: Cut Up a Brand New Duvet Cover

The duvet cover was just under 140 x 200 cm. A quick measure up revealed that a blanket around the 140 x 100 size would be just right, using the width of the duvet cover as the length of the new blanket.

I opened the packet, ironed the seams and corners flat (it was folded strangely in the packet), laid it out and then cut it in half to make two blankets. I used the closed off end, so I already had three sides nicely sewed up for me. I didn't have a big enough table so it was mostly laid out on the floor.

Step 3: Making the Pockets

From the back of my envelope I figured out that the easiest size would be to do 20cm square pockets. Then I could do a grid of 7x5 across the whole blanket. 35 pockets, each with three ounces in would make 105 ounces, perfectly in the range that I'd worked out. In fact, it was just under sized so I did everything to 19.5cm. Having a bag shape, I decided to sew six lines across, to make seven long pockets.

These I then filled with the first set of 3oz of beads. I started off marking the 19.5cm marks with a simple pin on the seam. But I soon found that the weight of the blanket (especially after two or three rows) pulled the whole thing sideways in the sewing machine. I got the tailor's chalk out again and for every row I marked out a line to keep to. It was still tricky as it pulled but at least I could see when it was going off line.

Step 4: Finishing Up

For the final row, I worked on the ironing board. As soon as I'd filled a pocket, I rolled the seam over twice and ironed it. I did this partly to make a neat edge where I'd cut it and partly to limit spillage as I was sewing. As you can see I used lots of pins to hold it all together.

That was it. I am completely in agreement with the prices charged for make to measure as this is quite a long, fiddly project. But it's also satisfying to do myself. And now, the rest of the family all want one too...