Bookcases, 3/4" ply. Shelves fit into 3/4" x 1/4" dadoes in the uprights. There are 20 "shelves". (some are tops and bottoms). 12 of those will be finished on both sides. That's 52 pieces of tape, by my count. Swingman has suggested a pizza cutter to make accurate edges. I could almost imagine doing that, but I now plan to do all of the "inside" finishing pre-assembly, and my available time is limited to (fractions of) weekends. Thus the tape could be on for weeks, which is apparently problematic.
I've been mulling this over, and this is what I've come up with so far (the usual caveats about my skill level apply):
http://www.flickr.com/photos/gdguarino/8378418997/in/photostream/lightbox / (use the right arrow to see two detail photos of the "jig")
I quickly screwed together two potential "guard" pieces to cover the last 1/4" of each shelf. I set the overhang by resting the jig in one of the actual dadoes. I figure I could clamp one side down "permanently" and either clamp and unclamp the other side for each piece, or possibly just hold it down manually. I might already have tested it but ran out of time last night.
I see some possible flaws in this plan. Upon looking at it, I wonder if stain and finish would build up on the edges of the thin plywood of the jig, or even seep underneath, "contaminating" the next piece to be inserted. This could conceivably be countered by covering the business end of the jig with shiny packing tape, or something else. I suppose I could use tape and wipe the jig ends off after each shelf face is done.
Then there is the question of the second side of the shelves. I could of course add a bottom "face" to the jigs to hold the shelf above the work surface, holding it of course by only the last 1/4".
So? The makings of a good idea? Or fatally flawed?