Loads of people buy resin bases for their miniatures nowadays, and whilst buying resin bases is nice and easy, you can lack variety - and with the ease of availability of products like "Instant Mold" its becoming increasingly easy to create your own.
Create a "disc" of card (or plasticard) that fits the top of your base, add your "detail" (either from a basing kit, or in this instance I created my own using simple sculpting techniques - and finished the set product with a selection of files and a scalpel) - if you create a "textured base" make sure it has plenty of time to dry/set and that it's been sealed with PVA (thats also been left to dry properly, at least 24 hours) - warm up your Instant Mold and take your impression of your creation (I always do at least two of each master for ease of production).
Press in your putty of choice, I use Milliput with Greenstuff mixed in - this makes it less brittle than using just straight Milliput - but unlike using all Greenstuff is better for basing/sanding/drilling/pinning etc - when mostly set, I turn them out of the mold and make sure they're nice and flat. Then mix more putty and start on the next lot
The "toppers" I've been working on could double as small flagstones or large cobblestones (users choice - they will work for Empire of the Dead, Carnevale, or more Modern Games like 7TV or Pulp City) - in this picture I have my latest "batch" setting.
(sorry about my Camera-Fu, it's weak at best).
I hope this gives folks some inspiration to create their own.