So with that in mind, I started out with some simple Spore Mines. I had some metal Spore Mines from some old Biovores, plus some plastic ones that came with the Battle for Macragge boxed set for 4th edition Warhammer 40k. So while I was waiting for the book to come out to decide what else I would paint and what it would be armed with, I painted up the Spore Mines.
Part of my concept for the color scheme of my Tyranid splinter fleet is that as the creatures age, they get darker in color. The basic color scheme is red skin with black armor plates and talons. Older creatures, such as monstrous creatures which would take longer to grow, would be a much darker red color than basic gaunts. Some, like Old One Eye, that look like they've been around a long time, would be purple. The Genestealers I've painted are purple, since they lie dormant on worlds for a long time preceding a Tyranid invasion, I imagined they would have been alive for a long time compared with the creatures spawned for the invasion.
So with that in mind, I needed to paint the Spore Mines a very light color. I assume that Spore Mines have been recently birthed and wouldn't survive to grow very old, so they should be much lighter in color than anything else in my armor. Almost albino, even. At first I tried making they a very light orange, as I had painted some Fleshborers on my Termagants a light orange color which looked pretty good. But I didn't like how that turned out. So I decided to go with a very light pink, with almost white tentacles with just a hint of pink.
I also wanted the tops of the Spore Mines to look somewhat transparent, almost like jelly fish. This turned out to be difficult to achieve, but I think some of them look a bit like you can see things under the surface. To get that effect, I painted on some blobs in Warlock Purple to represent organs or whatever inside the Spoor Mines. I then drybrushed Skull White over the pods and coated it with some gloss varnish. I then did another layer of Skull White drybrush coated with gloss varnish. It works better on some than on others, but I'm not sure there's really any good way to get the look I was after.
Here are some pictures of the results.
By the way, I would recommend against trying to paint anything using Games Workshop's Tentacle Pink paint. My jar of Tentacle Pink is some of the worst paint I've ever used. It's really lumpy and chalky, and it is almost impossible to apply without leaving chunks, and when you do, it takes many coats to cover anything. It's just horrible to work with. Then I discovered that if you mix quite a bit of Skull White with a little bit of Warlock Purple, you get a color very similar to Tentacle Pink, but that works 100 times better. I'm not sure why Games Workshop didn't just do that and bottle it as Tentacle Pink instead of the stuff they released. I just checked the Games Workshop website, and it doesn't look like they even sell Tentacle Pink anymore, so hopefully nobody else will have this problem.