I have made these prints, using a drypoint needle on perspex. I find that this method suits me very well. I am able to work away from the workshop and the plates are very portable. I generally print small editions, typically between six and ten. The other advantage of drypoint, I've found, is that you can develop the image further if necessary without the complexity of applying grounds and etching new marks. Perspex is a very sensitive surface and it is possible to create a great variety of marks.
I use Akua water-based inks, which wipe easily from these plates and clean up with just soap and water. I print on Fabriano Rosapina paper which, with Akua inks, only needs lightly sprayed with water to dampen it before printing.