Sorry no mac version yet.
My process for carglassing:
1) polyurethane seal the paper model at 3 coats, not to thick.
2) glue/hotglue seal obvious holes in the peice where resins will leak through
3) dont mix and match epoxy with polyester resin.
4) light coat of polyester (fiberglass) resin or smoothcast 300/325 brushed on to about 3 coats.
5) interior resining can now be done roto casting for initial durability or slush in some smoothcast or resin. x coats should suffice then if you want add the fiberglass clothing to a 3rd layer.
6) grind off any escaped resins/plastic from holes you missed
7) bondo with a spatula at all seamed areas, be frugal and work in layers
8) SAND repeat to #7 as needed
9) when you get to a point where its smalelr than quarter sized areas to bondo, start using a filler putty instead, glazing putty works great.
10) SAND and repeat to #9 as needed
11) Use a leveling resin like laminating epoxy as the final coating and sand that gradually getting to a finer grit then use steel wool
12) grind off and sand excess resins
13) paint
14) ???
15) profit
Another process:
1) Seal the outside of the model with polyurethane
2) carefully wrap the model as close to its surfaces as possible with tin foil
3) melt plasticine (non hardening clay)
4) pour melted plasticine into model cavity and let cool
5) remove foil and paper and you now have a base clay model to work from!
:lol 
