Trimming 3D faces with polymeshes

[scp]

I am currently trying to work out a problem with 3d and having seen the sort of things solved here I am pretty sure someone will have a good solution.

I have a 3d model (imported from Microstation) which incorporates twisting "ribbons" of cladding which have glass between them, which I need to calculate the sizes of. I have the "ribbon" plane, and was hoping to be able to offset this by a relevant dimension to create a slicing plane to cut the glass planes (currently 3d faces)
The "ribbons" sound similar to the concept of the mobius strip talked about previously, but a bit different in that I do not need to create the strip. The ribbon has come into autocad as a body, which I have exploded and run rulesurf across to create a polymesh surface
In addition to this, the 3d faces that represent my glass cannot be extruded to create a solid, even if I set the UCS to match the plane (If I run a polyline across the points I can then extrude this but I have about 500 to do...... a quicker solution would be good - if I really need to do it at all)

My questions really are this:
1 - Can I slice my 3d faces with my rulesurf'ed ribbon?
2 - Can I offset my rulesurf to create the new cutting plane?
3 - Can a 3D face be changed into a region or polyline
4 - If I can offset my rulesurf face, how would a make a solid of the ribbon

Any help would be appreciated - My basic 3D skills don't quite extend this far

[CADTutor]

Interesting problem.

Unfortunately, faces are very limited when it comes to modification. It will not be possible to slice or trim the 3DFaces and so I think the best option is to think about converting to solids.

Fortunately, 3DFaces can be converted to Regions. Just use the Region command and select the 3DFaces. Once you have done this, you'll be able to extrude the resulting Regions.

Hooray for Regions! :D

[scp]

I tried earlier on today to convert the 3d face to a region by using the region command with no luck - would the ucs need to be set to align with the 3dface prior to using the region command?

Also, (and the bigger problem) even if I can do that, how could I use the ribbon slicing plane? I have so far only been able to extrude along one spline, not two at the same time.....

Thanks for the help so far - Problems like this so often need another point of view.....

[scp]

Further to previous comments, I have tried converting the 3d faces to regions, but get an error saying that it found a closed, degenerate or unsupported loop.
This whole project is getting painful... - any thoughts on solutions would be appreciated

[CADTutor]

It is possible that the error applies to just one object. Did you try converting just one of the 3DFaces to a Region? Do they all give the same error?

[scp]

unfortunatly so - I have tried about 60 different ones and they all had the same problem.
This is not the biggest problem for me though - just takes more time to polyline them all then extrude.
The biggest problem is creating the cutting plane for the ribbon - if I could make the ribbon into a solid then I would be able to achieve the goal but I cannot find a way to do it yet - I tried creating faces to make a solid but could not find a way to take the enclosed faces to being a real solid (do not know if this is even possible
Thanks for your thoughts - The 3d face thing is driving me nuts