[member="Draco Vereen"]
It's a good idea though. I've seen [member="Popo"] do a lot of similar projects.
Once you get to a high enough Tier, I'd suggest doing tech submissions for each of the upgrades you wish to create and then creating a Unit submission that includes all of your submissions and which tanks they go onto.
Also, I've seen you pop up with a lot of good ideas but keep getting told the same thing... "Get to a higher Tier."
Don't let that stand in the way of doing these neat little projects you keep coming up with. I'd suggest working on development threads ahead of time that will help you get the technology and tier advancement submissions you'll eventually be needing... and just hold off on the actual Factory side of things until you're ready. Remember that the Factory is optional. There is no reason for you to not enjoy yourself and create the fun and unique toys you desire for your character. So long as you are not using them against another character in a roleplay (without PM'ing them and asking first), which would risk a report, you can really do about anything you want and never have to touch the Factory.
On the other side of things, you'd be surprised how hard it can be to get a decent contract set up. You'd also be surprised by what can qualify as a suitable development thread for a technology submission. They can be a lot more fun and interesting than just sitting in an armory tinkering with plates of metal and wire. Heck, I once used a Deadspace inspired "clear the derelict ship of zombies" thread as development for a starship based heavily on the planet-cracking space ships from Deadspace. It was a fun thread, though I had a lot of difficulty getting other writers to post in it. =/
Anyway... I guess I'm just trying to tell you to not let the Factory Judges get you down. I've done it enough to have a fairly strong grasp of how it's done, and have had to tell more than one Factory or Codex Judge that they are wrong. In this case? I think that [member="Silara Kuhn"] is wrong. There is a lot of money to be made in after-market add-ons for small companies. At tier one, you probably don't have the resources to build and sell an entirely new tank. What you CAN do is make a better tracking computer or create a chaff grenade launching system that can be easily bought and used to upgrade someone else's tank. (Edit) Heck, when I started Mandal Hypernautics on this board, that was all the company had the resources to do before Larraq got a hold of it. It proved to be a major plot point for the character and company as he fought to compete with MandalMotors and create viable alternative designs instead of simply selling parts to the larger company.
My evidence? Look at the history of the Jeep. It was designed during a major war by a struggling company. The Company designed it to fill a contract with the government. The U.S. Government ended up loving the design, but recognized that the company that created the design was incapable of producing the vehicle in large enough quantities to supply the military.
So? The Government bought the design, awarded a great deal of money to the small company, but then gave the actual production contract to other companies and instead only gave the designing company a small contract to build trailers for their Jeeps to use to haul supplies and Artillery around Nazi Germany.
Using the above as an example, you could easily use an Invasion or Skirmish thread where you participate as the initial justification, then do a Solo Dev Thread where you design a product, then do a contract thread where you try to sell said project to the Republic. That's three threads, an easily track-able story arc, and plenty of justification to create a respectable submission, fill a contract requirement, and write the whole thing off as a "project of sizable proportions" to get yourself a Tier advancement.
That being said, I've also seen some pretty horrible development threads get waved through. I'm talking... 20+ posts of flirting and only 5 posts of actual design or story getting used as "30+ posts of development". So you'll definitely get some brownie points for creating a story arc that makes sense to the creation of the actual product.