Complicated Weave Structures with Rigid Heddle
Anything that holds warp under tension is a loom and any weave structure may be woven on any loom. The main purpose of the rigid heddle is to act as a shedding device to create the 2 sheds necessary for the most basic weave structure: "plain weave".
Plain weave can come in many forms such as tapestry (weft faced) or inkle and rep (warp faced), and balanced weave (warp and weft are seen equally). Color effects can be used with plain balanced weave to produce cloth that looks rather complicated. More on that HERE.
If you want a more complicated weave structure, you'll need to use additional equipment. 4 shaft weave structures require either pick up sticks for each pick, string heddles on rods (less mistakes this way) or three rigid heddles. 8 shaft drafts require either string heddles on rods or a pick up stick. More on that HERE.
Personally, I feel that using string heddles on rods is the way to go when weaving complicated weave structures rather than using multiple rigid heddles or pick up sticks. In my mind it's easier to lift multiple rods (shafts) in their specific orders than to try and remember which rigid heddles go up and which ones go down or counting threads for each pick with a pick up stick, which is slow, tedious and prone to errors.
Here's some pictures from a cloth I wove using craft yarn and heddle rods to make a Hounds Tooth patterned cloth for a shoulder bag. Rather than use the rigid heddle to space the warp, I used "lease sticks" at the back near the warp beam to keep the threads in order. If you want to use your rigid heddle, DO NOT THREAD THE HOLES (the heddles). Make sure all the threads go through the slots (the spaces between the heddles). You will have to put 2 or more threads into each slot to get that to work.
I carefully used my stick shuttle to "beat" (place) the weft into the fell of the cloth.
Here you see the lease sticks at the back. I improvised by using what I had at the time, sishkebob skewers. Hey, whatever works, right?
Here you see the pattern forming. It's a 2/2 twill structure known as "Hounds Tooth". It consists of 4 dark threads and 4 light threads alternating. You weave 2 under and 2 over on the diagonal. Rather than use 3 rigid heddles for this, I used the heddle rods. This was a lot easier to work with, nothing complicated to remember and no mistakes compared to hand picking threads with a pick up stick or using the up/down of 3 rigid heddles. Not to mention, it was a heck of a lot quicker too!
Here's the cloth in action. I wove a strap for it and turned it into a shoulder bag.
If you'd like to weave this too, here's the weaving draft I used:
(CLICK TO ENLARGE)
If you need to learn how to read a weaving draft, visit my sister site: Joy Of Weaving
There's also tutorials on youtube. Here's one: