The Prometheus Class Carrier is a vessel designed in response to the Second and Third Battles of Arcadia Prime, against massive forces of raiding Eldar. During the battles, there was a constant duel between Imperial attack craft and those of the Eldar. Ultimately the attack craft proved at least as effective as all of the rest of the weapons fire from the Imperial ships, destroying a dozen escorts, two cruisers, and crippling a Void Stalker Battleship. This led to the development of a purely dedicated carrier vessel, with a complement of twelve squadrons of attack craft.
In order to maximize the impact of its attack squadrons, the Prometheus Class Carriers frequently employ torpedo bomber squadrons in addition to their regular bomber squadrons.
After scratchbuilding various Necron ships, I got on a kick of designing and converting/scratching building Imperial vessels as well. The Imperial Navy in the 40k Universe is based more on World War I navies than those of World War II or more modern times. While the Imperial does have some attack craft "carriers", they are really battleships or cruisers, that carry attack craft in addition to their regular armament. Other than the Forgeworld "Escort Carrier", the IN has no dedicated carrier vessel. Hence my invention of the Prometheus Class Carrier.
Aside from some sensor masts, prow skull/wings, and the launch bays, the Prometheus is entirely scratchbuilt out of plasticard.
My first attempt at the Prometheus included a bow made out of green stuff, and I got to the priming stage before I decided that I really didn't like the bow as it was (it really did stink). So I lopped off the old bow and replaced it with a mass of plastic rods, which I then carved down to make a new bow. there were a few gaps left over that I filled in with greenstuff. In the end, the new bow came out much better than the old.
I think the final result came out pretty well, except the one thing I don't like about it is the "height" of the hull--I think it's too "tall". (this is most obvious in the side view)