This project has been at one of those stages for a few months now where it seemed such a herculean effort to finish it that I just kept ignoring it. As it happened, once I got going with it again it wasn't anywhere near as hard or time consuming as I had envisioned. For those who haven't seen my other flying base projects, I'm personally championing the use of flying bases to make lovely themed bits of terrain for armies. The Tyranid one seemed an obvious choice for a spore chimney-type construct to be built around the flying stem, thus disguising most of it and adding a nice bit of scenery in to boot.
I haven't got a precise tutorial for this project but will outline the basics here. Using a decorating filler, build up the overall shape of the capillary tower. This is best done in stages to allow some drying between else it will start to drip and lose its shape. If using a powder mix like I did, I'd recommend making it as sticky as possible for this reason. I would also recommend covering the whole base in the filler/plaster for reasons I will come to later. use don't forget to sculpt the overall shape of the chitin plates while the filler is still pliable.
Using a sculpting tool, chisel, dremel or whatever you should make sure the basic shape of the model is as you want it. It doesn't have to be super smooth or symmetrical, and in fact making it less than perfect will enhance the organic feel of it. Once that stage is complete, use greenstuff or more filler to plug any gaps. Using liquid greenstuff, give the whole model a coat to bring everything together nicely. To add the tendons to the non-chitinous part I simply rolled greenstuff sausages and attached them like a web. I also added a couple of spirals to look like vascular bundles. As for the base of the model, I used a combination of slate and bits of plaster which had broken off the base to make it look as if the tower were bursting through the cracked earth. Sand was ideal to add texture and hide joins/gaps.
As for painting, I sprayed the model up black and simply used bases of steel legion drab, rakarth flesh and khorne red. I washed the red/drab sections with agrax earthshade and layered ushabti bone onto the rakarth flesh before washing with seraphim sepia. Once dry, I relayered the khorne red, highlighted with squig orange, glazed with bloodletter then rehiglighted with squig orange. For the base I drybrushed steel legion drab then karak stone. For the flesh I drybrushed ushabti bone. I painted the veins slaanesh grey, washed with druchii violet and then layered again with slaanesh grey. Where the base of the chimney met the cracked earth I used the technical nurgles rot to make it look suitably organic. Lastly, I matte varnished the ground and gloss varnished the chimney before tidying up the join with the small amount of clear, flying stem still visible.
Thoroughly pleased with the outcome and tempted to build some more spore chimneys as terrain pieces at some later stage. Cheers.