How to make a round thing without a lathe (plus model making tips)

Step 2 Make and insert a spindle

Using a piece of straight coat hanger wire push it through the cardboard disc so that it is on the axis of the shape you want to "turn", i.e. it is as close as possible to being at right angles with the top and bottom surfaces. If you have trouble pushing it through, make a (very) small nick in the surface with a craft knife first (just to break the surface) and to get started.

It should be a nice snug fit, but be able to turn. This is what you are going to stick you profile on to.