The use of these types of foundation came about as an attempt to reducing the amount of "work" bees had to do building their own comb, and instead concentrate their energies into honey production. It's strictly a one-sided expression of human greed when it comes down to it. Allowing the bees to build their own comb is a critical componet to supporting the vitality and health of the bees. We aren't doing them any favors by taking shortcuts in our beekeeping.
By using starter strips instead of foundation we allow the bees to act out and fufill their natural insticts and tendicies. A start strip can be many things, including wax, but using a stick of some kind is the best. Coating it with beeswax promotes the bees building their own comb down from the strip. Here's a good introduction to the use of starter strips from Kirk Anderson (AKA "Kirkobeeo") from Backwards Beekeepers:
I have never had any luck with stir sticks because the ones I find are always too think. Likewise, popsicle sticks or tounge depressors don't fit either, and balsam wood is to soft and wobbley. So, with the help of my knowledgeable father-in-law, we milled our own.
To make the strips you need some 1x12 wood stock, which is 3/4 inch wide. That width dimention will actually be the vertical demention of the strip as it hangs down from the top of the frame. Using a table saw you then cut the stock to a thickness (or "thin-ness" in this case) of roughly 3/16". Finish by triming to a length of 16 7/8in.
Unless you are very acurate in your cutting, each strip will have some minor variation to its thickness and length because of how small the measurements are. This is okay, because most wooden frames also have some degree of variation in them. One strip that might be slightly too thick or long for one frame might fit perfectly in another frame, just try more than one. Also, each strip should fit pretty snug; they should not be loose or pull out easily, and you shouldn't have to worry about using any glue. They should hold in place just fine. This setup was designed to work with grooved frames; it's not meant for frames with removable wedges, although they still might work. But, if you're not using foundation you won't want wedge or split frames anyway.
Here is what a homemade starter strip looks like installed into the top of a grooved frame...
And here is what beautiful, natural, bee-made wax and comb looks like, built off the starter strips...
This is a great frame because you can see the pollen (the darkish stuff in the cells), the nectar (the wet, glistening stuff in the cells) and capped honey towards the top. Fun!
This last picture shows a little better how the bees don't just build the comb off the starter strip, but actually incorporate the strip within the comb for greater strength.