Extrude Between Edge Anomalies

[MatthewMinnick]

I am using extrude between to create a multipatch of a subsurface aquifer.
I have a top and bottom tin[ATTACH=CONFIG]12088[/ATTACH]
The tins look good and are in the same projection, UTM.
The polygon I am extruding is also in the same projection.
When I use the extrude between I get a multipatch but it seems
no matter what I do I get odd edge anomalies, or out of place vertices and faces,
that look like spikes.  I have tried using various different polygons by buffering the orginal
and the same affect happens but can be at different edges.  Anyone know what is wrong,
or if there is a work around, or is it just a bad algorithim ESRI has implemented?
Using ArcGIS 10 SP3

[MatthewMinnick]

Ok I figured it out, so here is the answer if anyone else has the same problem.
If your tin has coincident boundaries with the polygon you are trying to extrude
then you can get these "edge effects" where nodes of faces are out of place and
the multipatch fails to close.  I figured this out by doing a inner buffer to the polygon
I was extruding to offset the boundaries with the tin.  The other solution, better in my
case since I need to keep the boundaries of my poly where they are at, is to extend the raster
interpolation beyond my area of interest and make a slightly larger TIN than my poly.