Commercially available kebab sticks, made of 2.7 mm Ø birchwood, 200 mm long, and pointed at one end, are an excellent source of cheap timber for scale modelling. They may be used to scratchbuild 1:16 scale wooden rammers for artillery, or staffs of polearms, flags and guidons. Birchwood skewers are straighter, and more convenient to work with than twigs of the same diameter, which need to be collected, stripped, measured, and sorted first. On the downside, industrially mass-produced kebab sticks are unrealistically uniform in appearance, and 1:72 scale palisade made from them often just looks like a wall of kebab sticks. Depending on the size of the construction project, consider using kebab stick timber for convenience, but with handfuls of similarly sized and shaped twigs thrown into the batch for added realism.
Historically, palisades would be round or quadrilateral, depending on which part of a tree they were made from. Young trees only needed to be cut into sections to provide round palisades of the proper length, whereas the large logs of older trees could be split and hewn to make several quadrilateral palisades. Both types would be used concurrently within a fortification, sometimes even within the same palisade, since a garrison preparing for a pending siege could simply not afford to worry about the esthetic appeal of their defensive works.