Possible to create a box in different planes?

I'm trying to draw a shop up for my backyard, and I have run into a problem. I am drawing the entire frame of the building for extra practice. It is basic light frame construction using 2x4's for the plates and walls, and 2x6's for ceiling joists, ridgeboard, and what will eventually be the rafters.

To draw these 3D shapes, I first draw a box in 2D, then use the box command in 3D to stretch from one corner to the opposite and pull it up. This works fine for objects drawn in the normal planes, but I can't get it to work on the rafters. IUf you look really close in the screenshot below, you can see the purple box that will become a rafter when I figure out how to extrude it or use the box command. It is towards the front of the structure, closest to you.

Any ideas? If I could just get one drawn I could copy and mirror to finish them out.

The way that would work for me is to use the ucs more effectively, Place the ucs onto the line work you plan on using (align ucs )then convert to a solid or region and extrude I hope.

Working in different planes, even ones at weird angles, requires reorienting the UCS. Personally, I like having the UCSicon in the "On" position so I know where I'm at. Others prefer to have it "Off" as they say it just confuses them.

I also like working in one of the four isometric views available (prefer the SE isometric).

Draw your rafters in elevation (front, rear, left or right view) and then extrude or presspull the shape to the desired width. Switch to an isometric view and position as needed.

I keep forgetting about Press/Pull. I'll have to write myself a note!

I figured out how to do it with drawing it on the default ucs, and then using 3D rotate to rotate it into position.

Still having trouble getting the spacing right. I didn't know the reason why frame boards (rafters, studs, joists) have to be nailed on 12,16, 24" centers until I got into architecture and construction. The reason is so that sheathing will run out and nail properly when covering walls and ceilings. same goes for sheetrock, which is also manufactured in 4'x8' sheets.

Could create a simple wireframe skeleton and then Sweep each frame member as needed (actually simply move-copy or pattern like members)

http://home.pct.edu/~jmather/content/CAD238/AutoCAD%202007%20Tutorial%208.pdf