Well the Admiral only had to complain for an entire year between ripping the old ones out and installing the new, but it got done...

I got tired of removing the original (?) smoke coloured acrylic companionway doors and storing them below whenever we were cruising and stretching out on  the settees while underway or at anchor since the depth of the doors had them banging into the lazarette/settee cockpit well walls.  Bought a sheet of 4' x 8' half inch Starboard and got busy.  Turned out that trying to duplicate the 3-D design was complicated and required 25 trips to the boat and back to the workroom, despite having the reassembled original doorframe at home.  Nothing is quite at right angles, tilted back, angled outward, overlaps abound.  Still, we're happy with the finished product, although the Starboard still requires cleaning, sealing and a bunch of UV-resistant 3-M 4200 applied as cosmetic filler in the gaps. 

WHAT I LEARNED

1. Starboard CANNOT BE GLUED/SEALED!!! It must be mechanically fastened.  The sealant is just for cosmentics, although it does adhere to both gelcoat, wood and aluminium.  Our local plastic specialist has had some luck with ShoeGoo (Marine Goop), but he's unsure if it will stick forever.
2. Finishing Starboard with sanding leaves a nice, slightly fuzzy finish THAT ABSORBS OIL/DIRT like crazy.  I'm trying a manufacturer recommended spray like ArmourAll that will need to be reapplied every year. 
3. Manufacturer of Starboard recommend only doing very smooth (razor?) cuts to have smooth edges, but I don't know how that might be accomplished.
4. I've been tempted to try 'flaming' the surfaces, but haven't gotten around to experimenting with a propance torch with flame spreader.
5. Screw points that approach the outer surface within about 1/4" will make a protrusion and can 'show through'.

Best of luck with your projects!