Should I give up?

Here it is in Vers 8, thanks Matt.

Got it.  So - are you trying to extrude this profile to a particular thickness?  (Sorry if you've posted that info before).  Or alternatively, can you post the picture of the earlier version that did work so I can figure out what you are shooting for?

Matt

This is the old version of the part I printed. When I made changes it no longer will print.

Okay, I think it's fixed.  See attached.

The issue is that your line drawing of the outline was not on one plane.  By connecting up some of the segments a number of smaller planes could be identified.  You then extrude those and cut through the resulting volume with a rectangle.

Select all the points/surfaces and the "Interface -> with selection"

At that point, delete everything you don't need, leaving the intersection with the plane.  You might need to clean up some segments as well.  If you hide the circular hole and rectangular hole before you start, you now unhide these and extrude them into the plane.  Repeat as above by deleting what's not needed.

At this point, you have your contour on one plane.  Extrude it by 9mm and you're on your way.

Hope this helps,
Matt

PS  You also seem to have had a lot of stray line segments left over from prior work, which may have been messing things up.

No problem - pay it forward

Every time I touch this drawing I knock it out of kilter. How do I ensure that any new lines are on the same plane? Does everyone have this much hassle? I've never felt this inept in my life.

Here's a snap of the design after you fixed it and I tried to evolve it toward the desired end result. I still need to make a couple of holes in the edges of the part for switches to stick out and a lid.

BTW, I want to make the top edges rounded (it is a pistol grip) so I downloaded the RoundedEdges plugin. Since the lid/cover will be fairly thin, like 2MM, I think I need to put the lid on the part, round the corners, then slice/cut the lid back off. In other words, the rounding will involve both the lid and 2-3MM of the edges as well. So, I will be wanting the best way to slice/cut the lid off after rounding.

Clear as mud?

Anyway, my persistent problem is keeping new lines in the base plane. If I mount the part on a big rectangle will that help? I can't tell you how much I appreciate you taking time to school me.

Here's the drawing:

I won't get a chance to look at the SKP file until tonight.  Usually what I do is draw guideline across a plane onto which I want to put a segment and then work off of that.

Also, there the Fredo6 tools, though I've not yet gotten very good at using them
  http://sketchucation.com/forums/viewtop … 78#p144178
It looks like "Tools on Surface" would be the one you want.  That said, I've not used it ...

As far as cutting off the lid goes : Once you've got the part complete (yes, I'd round the edges of the completed piece) I'd probably pass a plane through a copy of the part at the point where the lid and part meet.  Interface the two and delete everything except the lid.  Do the same for the body of the part.  When you're done you should have the original complete part, the lid and the body of the part.  There are probably more elegant ways of doing that, but I don't know them.

Okay, that looks like what I need. Thanks, Matt. You're great.

SketchUp is pretty good once you get used to it. Try searching YouTube for SketchUp Tutorials, they help a lot.

To slice an object for a lid etc the best way I've found is how mconsidine described it. You 'slice' an un-grouped object with a shape (rectangle), then intersect edges with model which will create the lines within your object.

If you're having trouble identifying planes on your object you can change your line colors to match that of the axis if they are on it perfectly. You can do this by going to Window>Styles>Edit and change the Color drop-down to 'By axis'. This is very helpful for identifying problem lines.

My first design in SketchUp was a rifle magazine so I feel your pain. Once you get the hang of it it is pretty good as long as you are not working on a very organic shape. Another tool to look into (if you haven't already) is the Follow-Me tool. Arc/Follow-me for your rounded edges.