I have put together a kit that includes everything you need to make one of these wall hangings, you can find the full rainbow wall hanging kits here. For those of you who don't love the colour options available with the kit, you can purchase this half kit, and add the wool roving colours of your choice then source your own acrylic yarn for the tassles.
This half kit includes;
A piece of matting (55cm x 40cm)
150g of warm white wool roving
1 x 4mm plastic crochet hook
Optional: choose 40g of additional wool roving for $3.90 each
Instead of weaving the roving through the mat, I use a crochet hook (included), put it through the mat from the back to the front and pull a small section of the roving back through the hole. I've added some pictures to show what I mean - you can see my tips here.