so judging from the images you have 3 intersecting polygons/edges/whatever and you don't want that, i guess. maybe you should use an "Inset" Command first, like shown here - before you do the "Extrude"Command. maybe that could solute your problem ?
thank you for your replies. i think the example i provided above isn't really clear. so, just imagine you have 4 edges, which are not connected to each other in any way, and you want to make a body (an edged column, with 4 polygons) with them. it'd be like creating a polygon from/with 4 verts, but i want to do this with…