Hi YHWH_777 - for the case of a box you can turn on control points with Edit > Show pts and modify them like Marco has shown.

For the case of a cylinder that won't work though because the cap of a cylinder is a trimmed surface. There is some explanation on trimmed surfaces and control point editing in this FAQ entry here:

http://moi3d.com/wiki/FAQ#Q:_Why_does_show_points_work_for_some_objects_but_not_others.3F


Most of the time though MoI is more oriented towards constructing the object that you want more right from the start, rather than modifying some other object to get what you want.

So for example in the case of a tapered box, you could draw one rectangle at the base, and then a 5x5 rectangle at the top and then use the Construct > Loft command to build the tapered box directly that way. If you wanted to do a tapered cylinder that would also be the way to do it - one larger circle at the base and a smaller one at the top and then Loft to create it.

- Michael