Been working on a tower building for the Tatooine table...
I made the building in 3 stages; top, middle and bottom sanding and smoothing the foam until I was happy with the design and fit. Wood glue is used to attach the pieces together and works really well on this type of material.
To make the domed top, I cut away and sanded the polystrytene ball to around a third and then filled the resulting hole with some scrap foam, sanding the piece down to create a smooth transition. I'll use filler to address any gaps and it should look cool with a base layer of paint applied.
Until next time ;)