You CAN make this loom for FREE! (And since it makes it's own opening for the yarn (called the "shed" in weaving terms) kids like it better than the potholder looms they might be familiar with. (They don't have to weave every stitch between the warps, they just pass the shuttle through.) It is really just a simpler version of a rigid heddle loom that many beginning weavers start with. If you deal with lots of kids and no budget for supplies, this is a favorite recommendation of mine.
Materials:
A piece of stiff cardboard.
String
A kabob stick
Fork, hair pick, or pet hair pick.
How to:
Slit the cardboard at the top and bottom.
Any increments you choose, say every 1/8", 1/4" or 1/2" for starters. (This is your "sett.")
Run some sturdy string/yarn back and forth through the slits. You can use anything for this "warp". For the photo, I used a product called "carpet warp" because it is strong, comes in many colors, and is cheap.
Run a piece of flat cardboard through alternating strings (warps) and slide to the bottom. This gives a straight edge to your woven piece.
With the kabob stick and a piece of string 3-4 times longer than the width of your warped area, you will be threading the sting through the alternating warps. Start by taping the string off to one side. Loop the string down to capture a warp thread, then loop it around the kabob stick. Repeat with the next alternating warp thread until you have laced your way across the warp. When finished, tie the ends of this string to the kabob stick and secure. There needs to be a fair amount of slack in this laced-string between the stick and the loom. It will not work if it is laced close to the surface of the warp.
When you pull up on this stick positioned in the center of the loom, you will have clean "shed" or opening to pass the shuttle of weft through. (You will be passing the shuttle BELOW the stick and where the strings pull up on the warp threads.) When you slide this kabob stick up to the top of the loom and let it go slack, you will notice that the alternate set of strings is slightly higher. (I am using the second kabob stick on top to slightly raise these alternate strings). I call this the "lazy" shed, because you don't have to do anything to make it happen. Just find the opening with the nose of your shuttle and weave. I also call this the "lazy" shed because I was introduced to that term when taking a Navajo class with Pearl Sunrise!
By moving the kabob stick into position when needed, and then sliding it back up to the top (out of the way) you can operate this loom just like a rigid heddle. The only difference is that you will need to pack your weft in using the fork or a hair pick at the bottom edge of the loom.
I hope this helps!