USE OF WOODEN STICKERS TO STACK lumber for drying will sometimes result in mold or bugs between the sticker and the lumber. Store-bought stickers work well, but are expensive.
An alternate solution is to use ¾" SCH40 electrical conduit, about $2 for a 10' section at a local home supply store. It can easily be cut into required lengths. Its advantages are: small contact area with the stacked lumber; very rigid; bugs and mold don’t find it tasty; sliding boards onto the conduit is very easy because they tend to act as rollers and are much easier than other types of stickers.
However, if the wood is going to be stacked on anything but level ground or the whole stack is going to be moved with a forklift, the roundness of the conduit will result in a pile of lumber that rolls onto the ground (usually into the only mud puddle within 100 yards).
To solve this problem, purchase 1½" conduit and cut it down the middle, making two stickers shaped like half circles. Make a jig using a scrap piece of 4" x 4" x 10". Bore a 1½" hole through the center of the 4" x 4" (unless you have a long bit, you’ll probably have to drill from each end). Raise the blade on your table saw to about 3" and cut a slot down the middle, bisecting the center of the bored hole. Next, attach the jig to the fence of the saw over the blade (make sure you cover the exposed blade completely). To use the jig, simply turn on the saw and feed the conduit through the hole bored in the jig. This will give you two stickers for the price of one.