Classic-Castle.com

what is the best way to make a dome about the size of a baseplate? i am more concerned how it looks on the inside that the out. the concave part not the convex

I assume you mean a 16x16 baseplate, correct? Well, the simplest way would just be to stack bricks and try to create as symetrical a shape as possible. Remember to stack the bricks in such a fashion where, for example, the first 4 layers move inward by one stud, the next two by two studs, and so on. This creates a rounded shape. If you moved inward by the same amount each layer, you would simply end up with a pyramid. See what I'm saying? I could whip up a visual if you really want it.

One of the members of my lug (SALUG) has a great tool on his website for making spheres.

Here it is.

eKnight

I spotted this a few days ago. This is too big, and looks better on the outside than the inside, but i'm posting it anyway. It might give you some ideas.

http://www.flickr.com/photos/redcokid/8514256675/