This is a LDD red version of the Mid Scale Star Destroyer 8099 and is based on EU Star Destroyer; The Errant Venture. Let me tell you this was a pain to make on LDD due to the awkwardness of joining various hinge joints and aligning the upper and lower parts. Some parts I had to remove and others I had to add on to get it to all to fit together.
As for the back-story; in the Star Wars EU the Errant Venture was an Imperial II Star Destroyer, privately owned by the smuggler Booster Terrik; and for many decades was the only ship of its class to be privately owned, distinguished by its red colour. Originally commissioned in to the Imperial Navy as the Virulence, the ship was captured by Terrik during the Bacta Wars and under his command played a vital role in the Republic's capture of the Super Star Destroyer Lusankya.
Terrik who found commanding an Imperial Star Destroyer enjoyable decided to keep the ship. Despite the Republic's unwillingness to leave such a powerful war-ship in the smuggler's possession, Terrik was permitted to keep the Star Destroyer on condition that all its heavy armaments be stripped down to what was permitted for a civilian craft.
To persuade Terrik to agree to this he would be allowed to sell the weaponry to the Republic which netted the smuggler captain eighteen million credits. After the deal was complete Terrik then renamed the ship; The Errant Venture and turned her in to a wandering shadowport and mobile bazaar of all sorts.
At some point the Venture was hired and refitted by the Republic for a covert mission in to Imperial territory. Terrik laid down a few conditions. One was that he be allowed to keep all the military hardware intact, second was that to distinguish it from any other Star Destroyer, the Venture would then be painted red.