Stop the chronometer when the visual star vibrations stop. The directions here will demonstrate how to build and test the efficacy of a tripod tray on a common type of collapsible aluminum tripod with plastic spreaders. Note that this project is simplified by the fact that the tripod was designed to accept a triangular accessory tray. Tray and back of spreader-system. The tab is meant to help center the tray and the slots can accept protrusions or bolts that prevent the tray from slipping.
Spreaders meet at a central joint that has a hole in it.
Your project will have to be customized if your tripod doesn't have these features. Project Material Sizing information for this material is given below. Select a piece small enough to fit between the legs when placed on the spreaders but big enough to simultaneously cover all the raised tabs. I choose a thickness that allows the tray to fit in an equipment case I use, but thicker wood has a better dampening effect. The wood will be worked into a triangle with flat corners.