Hi Gunter, so maybe give this a try - you can select all the polygons and extrude them at once to produce a bunch of extruded solids. Right after doing that, the generator curves are still selected and either delete or hide those to get them out of the way.

Now to open up the top or bottom of those extrusions, go to the Scene browser, Types section. On the entry there for "Faces" hold down the Ctrl key and left-click on the selection dot area on the far right hand side of the item (as described here: http://moi3d.com/forum/index.php?webtag=MOI&msg=4438.21). A little filter icon will appear. This activates a selection filter on this item which means that only faces will be targeted for selection while this is set. You can now go to the Front or Right side elevation views and do a window select (starting on the left and dragging the mouse towards the right, that makes things only completely contained inside the window to be targeted) around the top or bottom area of those extrusions. Now just those top or bottom faces will be selected and you can now hit Delete to delete all of those. Now push Escape to clear the selection filter.

So now that has prepared each extrusion with naked edges to be targeted. A small customized script can help with the targeting - this script will look for a selected "joined surface" object (like one of these open ended extrusions that you've just created), switch selection to its naked edges and then run the nsided command. Then you need to right-click or push enter to finish the command and then click the next extrusion, push the shortcut key again, push enter or right-click to finish the nsided command, etc... This still needs individual actions for each piece but it's narrowed down to a click on an extrusion and then a keypress and another click for building each one. It should go pretty quickly. Probably do it in the Top view so it's easier to click on each extrusion.

To set up the helper script, go to Options > Shortcut keys and add a new shortcut key, and paste in the following for the Command part of the key (on the right-hand side):

script: /* nsided helper script */ var breps = moi.geometryDatabase.getSelectedObjects().getBreps(); if ( breps.length == 1 ) { var brep = breps.item(0); moi.geometryDatabase.deselectAll(); brep.getNakedEdges().setProperty( 'selected', true ); moi.command.execCommand( 'nsided' ); }

- Michael