Dr. Merkury’s Lab offers some templates for making 28mm scale modern style buildings. Print them out, and then use them as guidelines to cut your walls from foam core.
Modeling
Adding Cloaks To Your Miniatures Using Green Stuff
Here’s a photo tutorial on adding cloaks and capes to your miniatures using green stuff.
Modeling Ironclads
Here’s a photo tutorial on building a model casemate ironclad.