10/04/2019 edit
I won the weaving contest of Instructables with this project!! In this instructables, you will find the files I made for 3D print my own loom (and a lot of other details about this project). I’ve added my joining method at the end of these notes.

A stash busting project. Every square I make is like a small universe itself. I choose the colors with an idea in mind, and the idea runs and runs as I weave the square. It is quite contemplative and very concrete at the same time - a pretty good combo in my opinion.

I wasn’t attracted at first sight by pin loom weaving. I like the big scale of my floor looms, the long lengths of thread I wind on the rotating bobbin. Cutting yarn and threading a needle, I doesn’t feel like weaving to me.
Then I accidentally saw a LionBrand video about the Martha Stewart loom Kit. There is no needle involved, just a crochet shaped tool, and a crocheted looking finishing. You don’t have to guess the length you will need, because you use it directly from the ball of yarn. There is literally no loom waste. I had to try that!

I made the 3d model of my very own pin loom and printed it. I use a 2mm knitting needle I bent to pull the weft through the warp.

Here are the Lion Brand videos :
How to warp
How to weave the weft
How to bind off

Actually, pin loom weaving that way feels like knitting or crocheting. You use the yarn from the ball, without cutting it, and you pull loops of thread through others. As you have a crocheted border in the end, you can knit or crochet around the square without preparing work. And that’s how I intend to put the squares together.

07/02/2017
35 squares done! I don’t know yet where to stop. I just choose colours and weave them. It is fairly addictive. As soon as I finish one, I want to try a new colour combo!

13/02/2017
60 squares done! I think I will make 144, to be able to make a 12x12 blanket. I make 5 squares per day, the stack is dangerously rising… Some pictures added!
It however looks like it will remain a lot of my stash of ugly yarns…

28/02/2017
114 squares done, I hope to make all the 144 squares by Sunday (today is Tuesday). Then will come the time to put them together.

05/03/2017
It’s Sunday, and I have now a huge pile of 144 squares! Coming soon : studying the assembly, which yarn, which needles…

10/03/2017
I will use Drops Eskimo to join the squares, with 6.5mm needles, in garter stitch.
I do not intend to list all the yarns I used for the squares, but a substantial number of leftovers from my recorded stash (in Ravelry) has been swallowed by this project. All the 144 squares weigh 4kg, which makes 28g per square.

24/03/2017
Half of the blanket is assembled, but I need more Drops Eskimo to finish. I’ve added a picture.

01/05/2017
I eventually finished the blanket. It is huge, quite heavy and really beautiful. I lined it with some polar fleece I had in my fabric closet, so it’s also a warm blanket.
It is a great finished object, but there are some details to improve. I used several threads of yarn for each warp/weft, and the difficulty comes from the number of threads to use, considering I had a lot different types of yarn. I tended to make the warp/weft bigger and bigger, so the squares became heavier and stiffer. I feel like it’s a natural tendency of mine…
Beside that, the blanket is really heavy, and it could be a problem. It doesn’t fit in our washing machine, it’s way too big! For such a large blanket (240x240cm), lighter squares would have been a better choice. Actually, it would have been more reasonable to make a smaller object, to experiment the new craft and apprehend the medium. But as soon as I decided how many squares I wanted to obtain, I was only determined. No place for reason until the end…

I love it anyway, obviously. Once I have been able to spread it on the garden grass, it was like it had always existed, like we had always owned it. Which is actually the case, as Mehdi pointed out to me, since I had those yarns in my stash for years. We can now enjoy them, even those I disliked !
I am really proud of my knitted assemblage, it looks neat, and that’s precisely what I was aiming.

Joining method (knitted) : This method will allow you to join and bind off at the same time.
With 6.5mm needles and DROPS Eskimo, pick up and knit 21 stitches along one side of a square. Knit 5 rows. You have now 6 rows (or 3 ridges) of garter stitch, with right side facing you. Take the square to join and place it ahead of your work, wrong side facing you. In other word, the two squares are right sides together. Insert your right needle into the first bound off stitch from the square to join, then into the first stitch on your left needle. Knit one stitch through the two stitches, the one from your knitting then the one from the square to join. You got one stitch on your right needle.

Repeat : *Insert your right needle into the next bound off stitch from the square to join, then into the first stitch on your left needle. Knit one stitch through the two stitches. There are 2 stitches on your right needle. Pass the first stitch over the stitch you just worked. There is one stitch on right needle*.

Repeat from * to * until there is only one stitch remaining on the right needle. Cut the yarn, pass the end into the loop and pull to secure.

Join the twelve square of one stripe into a long stripe, do it for the twelve stripes. Then, do the same to join the stripes together. Pick up 21 stitches per square and 3 per garter stitch border (one stitch per ridge), which makes 285 stitches to pick up along one stripe.

I also added a border of 6 ridges of garter stitch (12 rows) around the whole blanket.