Modeling Operation Error: Sweep self intersects - I can't work out how to fix it.

I've done some reading and I vaguely understand the issue but I can't seem to find the problem with my drawing yet when I try to extrude it gives me one.

Here is the file:

Thinlines.dwg

And this is what I am trying to draw, but with different dimensions/spec.

Some more info for the guitar nerds

I have got ahold of some threaded magnets and I can't find a plastic bobbin with holes that are small enough to tap a thread so I am planning to 3D print one.

Welcome to CADTutor.

As fate would have it, not only does the past recede, but all too often, the hair goes along for the ride.

The best electric guitar I ever had was a first generation Tele Thinline, an awesome instrument, perfect for finger picking.

I liked it much more than my Pre CBS Strat, which as a finger picker, was not as well suited to my style of play.

On a strat the middle pickup gets in the way, unlike on the original single coil version of the THINLINE.

I had always loved Teles, and ridiculed the Thinlines from afar, until one day I was setting one up for a customer of the guitar shop I managed in L.A., when lo and behold, I learned the error of my uninformed preconception.

I promptly found and bought one, which I loved, sorry I sold it during downsizing before moving across the pond.

The problem you are having is likely exacerbated by your having drawn this with splines.

I used the SPLINEDIT command, could/should have used the PEDIT command.

I chose the convert to Polyline commandline option, and once that troublemaker base plate was a polyline, it could be EXTRUDEd.

There is no need to use SWEEP (because that is usually used in non rectilinear situations, like along a curve).

Easier still than the EXTRUDE command is the PRESSPULL command, which will also create a 3D Solid,

but it is much less particular about the selection of entities which you choose to define it.

The defining entities do not need to be closed Polylines, but can be numerous disenfranchised entities and mixed object types.

They should be co-planar though, and make sure your UCS is oriented in such a way that you will be dragging along

the Z axis, in either direction, up or down. Not sure why I am having such a hard time Radiusing the straight portions,

funny that the curves will, and the straights won't accept the Radius, which is sufficiently small that it shouldn't

be problematic.

Splines are great when you NEED them, otherwise I would suggest using POLYLINES as much as possible,

use appropriate OSNAP settings, and for the last segment of one, use the C command, which will CLOSE the polyline automatically for you.

If you EXTRUDE an OPEN (as opposed to CLOSED) polyline the result will be a SURFACE, not a 3D Solid.

What program did you use to draw this?

Why didn't you use AutoCAD to draw this simple geometry?

Even your circles are splines?