With the bases ready and the plan in place it is time to build up the cliff and the castle. The proces for this is quite simple. I have a few large blocks of dense polystyrene (never ever ever ever use the white bubbly stuff! In my experience it will destroy itself during gaming no matter how well you seal it off with glue and insta-filler). Just grab a very sharp knife cut of a (~10 cm) wide strip of polystyrene, and divide it into smaller chunks (~10cm x 10cm). Cut a few smaller bits of and make sure to always cut of the edges and points of each block. Then get your hot glue gun ready and start fixing the block to the table (yes hot glue melts polystyrene but not by enough to make me care and its almost instant drying time allows you to work at speed).
First of was the upper cliff bit for the keep itself. I made it first because the workbench was still empty at that point. Next up were the the ascend piece and the cliff bit, also because of workspace consideration. Last up was the big cliff and the castle.
I marked of the ascend in the corners by gluing a few 10x10cm blocks atop each other (2 for the start and first corner, and 3 for the second corner). and I cut one larger piece diagonally to make the ascend out of one piece. That prepared I let my mind wander as I glued pieces of polystyrene on top of other pieces. I marked out space for a large mysterious cave entrance to one side and made sure to glue supports for the building on the inside. Here are a few work in progress shots.
Next up cutting and covering it all up....