not sure where you are having issues, the parts that make up the drone, or the parts that attach to the drone to make a convincing marker light?
Depending on your friends and what you have access to for bits, it might be an idea to use
SM tank hatches. Another option would be to snoop around and find out who in your area has a one-shot-coffee maker. Specifically, what you are looking for is the Nescafe brand:
the pods are constructed in this way: plastic top, fill (coffee/tea) aluminum foil/filter, and at the bottom, a small plastic circular filter.
notice the black disk at the bottom. That is the part you want. It has the right size and shape to use for tau drones, and actually looks all technological, because the filter components make it look like techy projection vanes and circuitry. I won't be able to get pics up of what it looks like till i get in to work and feel the need to make a coffee. Just ask around with your friends, you're looking for the plastic filters out of the Nescafe coffee pods.