Thought I'd share some of my terrain as I've used this forum many time for inspiration, maybe someone could do to same from my ideas...
Turret - a couple housings pulled out of a xerox ink canister and a pair of Cat5 Heads + glue and paint
Overlord Dropship - Usual Easter large egg + 4 wire end caps + Bottle cap
Trees - Luau Trees from Summer cupcakes (yummy desert with awesome battletech Trees) + Dollar Tree Checkerpiece + Penny (melt the bottom of the tree and stick to checkerpiece with a penny glued on the bottom for weight
HPG - Top of Chrystal Light Container + some random computer parts bent to my need + Base of Dollar Tree Wine Cup