You could also build a workbench but I prefer a mobile structure. This way I can move it inside the tiny house when I am working on the interior, up to the loft when working up there or outside for the siding and such. One of the best innovations to come out recently is the Keter worktable. Here is an image.
It folds down for easy storage and transport and it is very easy to setup. It is pretty steady and a good work surface. At about $70, it is not to expensive and will save wear and tear on your back. There are a couple youtube videos online, they will explain its use better than I.
I would also purchase a set of sawhorses. You will need sawhorses to cut long sheets of plywood or to paint your siding boards.