The ground scale I use is 4cm=1km, so a battalion sized unit ideally has a base width of around 4cm, as one kilometre is the minimum frontage such a unit would occupy.
Leg infantry are mounted on 4x4cm bases like the Italians above, All photos have been taken against my cutting mat which is marked with a 1cm grid. Hopefully this will help give readers a better idea of sizes. The dark square at the rear left of the base is the mount for the unit's strength point (SP) marker. I'll cover SPs in a future post.
My older (veteran?) units are based on balsa (3/8inch thick from memory). I like fairly thick bases for two reasons: Ease of handling - which helps to preserve the toys and to help set the stand apart from the terrain - this helps to overcome the notion that a toy tank or whatever represents a real one. It doesn't. Rather it represents a battalion-sized unit of, say 40-80 tanks. All of this can really annoy self-styled 'proper' gamers. Do I look bothered?
More recent models have bases cut from foamcore board. This is about as thick as the balsa bases but a hell of a lot quicker and easier (and cheaper!) to cut. I use a steel safety rule and a Stanley knife with a fresh blade.
When building units it is always best to consider what looks more or less 'right', rather than what is 100% accurate. A case in point is this Italian lorry. This is actually a 15mm (Peter Pig resin & metal) model, but the real thing is so huge that this toy looks OK with 20mm figures.
Coming soon - SP markers.
Remember that if you'd like me to run a post on a particular Megablitz unit (or unit type) feel free to ask.