Before starting the mass production of the Plague Zombies I have to build 70 hollow bases first. Yes, I could just have bought some more of the scenic bases I got for my Plague Bearers, but this would have been too costly. So I went the cheap way and turned a bunch of old 28mm round bases into hollow bases for creating the swampy subsoil.
Creating hollow bases isn't too complicated.
1. Take a standard base and drill small holes on the outer edge of the upper base part. Make sure that distance between each hole isn't too big (I drilled around 20 holes per base)
2. Take a hobby knife and cut out the top part of the base. The drilled holes will help you not damaging the rim (it might dent or even break when you put pressure on the base)
3. Glue the base rim on 0,5mm thick plasticard (with proper plastic glue with solvent that melts the plastic). This will give it support and stability.
4. Carefully remove the remaining plastic flesh with a hobby knife and sand paper.
5. Cut away overhanging plasticard and sand the base carefully to remove irregularities.
1. You can glue the base on the plasticard right away and then start drilling and cutting. Actually, this way you will have the support from the plasticard right from the get-go.
2. For the clean up part you can use a Dremel or similar electric tool to remove the remaining plastic pieces. It is much faster as you sand/melt the plastic away, but you also have to be careful to not damage the rim.
Granted, it took me a couple of hours to get the 70 hollow bases done, but figuring out how to do them in a efficient way was a lot of fun, and in the very end it was much cheaper than buying blank ones.