Word of advice Lawler....don't think, know
...... what you want to do for your diorama. It will save you alot of work in the long run. If you have a preconceived idea of how you want to display your vehicle, it will make the base building a more pleasurable experience, allowing you to work towards a goal rather than an experiment.
If you have a plan, then you can formulate the steps to get you to your end result.
Sketch your ideas out or have them in mind when you begin. This will tell you how big your base is going to be. What materials you'll need and then where to start. In short. What are you trying to say? Are you looking for a simple display of your vehicle, using the base as a sort of frame and just enough ground work to put it in a setting, or are you making a "photograph or snapshot" of a moment in time (or imagination)?
Once you figure what size base you'll need you can look into things like
- Do I need to cut my base to size?
- Can I use something already made? (tile, pre fab base, picture frame, tree branch, etc.)
-Will I have to build up my base?
-Can I leave it flat?
What environment is your vehicle going to be in? If its winter then you have the varying conditions that are associated with it. Deep snow, no snow, some snow. With snow you don't have to worry about things like grass etc. Or you can make mud (ahhhh spring in Russia... the mud, the rain, the partisans) still no grass just lots of mud.
You get my drift.
Your ground can be somethig as simple as a road, piece of grass, section of field, ditch, cliff face, whatever. You can start by doing simple contours with sculpey, celuclay, plaster, wood, dependent on your subject.
Big contours can be made with foam or wood to build up elevations and then covered with spackle, acrylic medium, plaster, celuclay what ever, and then painted with the colors appropriate to your choice of ground and then covered with the ground detrius (leaves, grass, mud, sand, dirt, pebbles.
Washes of white glue are good for setting dirt or sand in place or sprinkle this stuff in to the wet plaster etc. before it dries. At the same time you can add things like logs, big rocks, rubble, trees, tall grass (made from cisal rope or hemp rope) or apply commercial products like static grass.
Mind you the fun in all of this is figuring ways to make this stuff look like what you intend. Everyone has their recipes for ground materials, snow, ice, etc.
Whatever wood you use, make sure it is painted and/or sealed before you get started or it will come back to bite you later. Some guys build on a sheet of acrylic and then mount this to the base. Water (from the celuclay or plaster or modeling paste) doesn't effect it like it would wood or mdf and saves your base from uneccessary handling or damage while you are working on the ground material or building up the "setting".
I highly reccomend Shep Paines book on building dioramas. It is very helpful and chock full of ideas and hints to get you going into making top notch vignettes and dioramas.
Good luck with this and dive in. The fun is in the journey.
Mike