It's not easy. Some may claim designing original mecha is easy, but it's anything but simple. The pitfalls and temptations and simply the amount of effort it takes makes it a trial to design a mecha for a fanfic. Particularly for the After Colony timeline.
    I'm relatively certain just about ANY Gundam fan has designed, or tried to design, their own original mobile suit/gundam, or a variation of a preexisting design. Unfortunately, most of these fan-designs fall into the "Mary Sue" category of mecha- superpowerful monstrosities that pack guns in any possible place, super armoring, shields, or speed, and so on. While certainly egotistically pleasing, a truly 'invincible' gundam is worthless for any sort of serious fanfic. Why? Because there's no story then, if the supermecha can trounce all the opposition without any effort. Take a look at the Gundams in Wing- they are anything but invincible! Overpowerful as opposed to the mass-produced suits, true, but they're not completely perfect. They do take damage, and can be blown up (by means OTHER than their own self-detonation devices, to boot!), and they can be outnumbered or tactically outmaneuvered. (Zechs vs Heero in the first episode is a good example of tactic vs power). In order for a story to be plausible, the mecha can't be invincible. If that means not adding that extra buster rifle or leaving off on the machine cannons of doom, fine. Give your gundams some weaknesses. They can make for stunning mobile suit battles and excellent plot points. (Plus pilots can get SO emotional when something bad happens to their mech!)
    Another major stumbling block is the basic know-how. You need to know your weapons and how best to distribute them. Buster rifles don't fire rapidly, and a single suit can't carry much more artillery than Heavyarms Custom. It may be tedious, but track down information on other mobile suits or mecha for the animeverse you're designing/writing for. Sadly, this lack of knowledge shows slightly in some of the earliest mobile suit designs for A New Era. The Serpent II is basically a very cheap knockoff of the original Serpent, and its design has only recently been adjusted to bring it back within the realm of what is possible in the Gundam Wing universe. Research, research, research! I can't stress this enough. There are hundreds of web pages out there with detailed information on the mobile suits, and also on the different weaponry they use. The Mechadomain or the Gundam Project are very comprehensive sites and those two alone can satisfy nearly any mechanical research you must do. Even if you design your own weaponry, still look through what already exists, and figure out if it's truly possible.
    Weaponry... the stuff that truly makes or breaks the suit. Granted, appearance and speed certainly helps, but let's face it, the weaponry contributes largely to the appearance and performance of the design. Wing wouldn't be Wing without its buster rifle, Heavyarms wouldn't be itself without absurd amounts of bullets and/or missiles, Shenlong and Altron just wouldn't be as cool without their dragonfangs, and where would Epyon be without the heat rod? The weapons themselves may be cool, but you really can't pile them all one any design. Gundams (particularly those in the After Colony timeline) have their own themes, shown through design and through weaponry. This may leave them with a glaring weakness, but in the long run (particularly when complimented by the addition of another suit that has a different set of abilities), it can overall work much better. Be inventive! Try new things! If they can make beam sabers, scythes, glaives, and tridents, think what else could be done! Boomerangs, naginatas, tessans.... a little inventiveness can go a long way to customizing a design so it stands out as something different. Thinking outside the usual weapon ideas can help, too. A weapon like Deathscythe's buster shield seems unusual at first, but surprisingly effective. Think different, break out of the box! Anyone can come up with a twin-megacannon, but who would have thought to mount an acid cannon on a suit?
    Sometimes, to make certain mecha (or spaceships) possible, you have to invent some totally new technical jargon. If you're writing in the AC timeline, don't go reinvent the Minovsky particle. It's been done to death in the original Gundam timeline, come up with something new to solve the problem. For us, there was a problem with interplanetary transport (and technically communication as well), and we used that to create a new kind of engine. The "High-Energy Output (HEO) Hydroengine" was our solution. A new technology that, while in the real world is probably impossible at best, works nicely for our needs of an expensive new technology that can speed up travel between Earth and Mars and Earth and Venus.

    Now, on to the semi-ranty part of this meandering shpiel- actually writing a battle. As those of you keeping up with A New Era know, Episode 26: To the Stars Through Hardship, focuses almost exclusively on a rather large battle between "rebel" Preventers (and the Maganacs and even some terrorists), and the Preventers following Selvaggio's commands. It was not an easy episode to write, especially with the "more vivid battles" from the voting booth echoing in our heads. So, before we sat down to write the episode, we again went back to our source material- the TV series (actually, Wing and the original Mobile Suit Gundam, since it's on now). Both shows rely in some small part on stock footage (particularly in the older MSG)- reusing sequences. (The Gundam launching from White Base, Dopp fighters falling apart midair, Taurus mobile dolls evading fire and shooting back at some enemy off screen, Heavyarms shooting at SOMETHING off screen to the right, etc). While that all looks nice when done right in animation, you can't reuse text in the same way. That's just tacky. So that's one option out for us.
    If you pay attention to the fight sequences, you'll notice something interesting. They don't just show the mobile suits battling back and forth. They break it up considerably. Either by showing the pilots in their cockpits exchanging taunts or something, or by cutting scenes completely away to something else. (Look at Heero vs. Zechs in the Antarctic- at some point somebody says they've been at it for 3 hours but we only see fragments of it, since they skip around to other stuff, including the base monitoring the fight, or to Relena, and to Acht's goons getting whomped by Trowa using Wing...). Breaking away and shifting the focus rapidly helps generate a sense of a fast pace, a lot going on at once, a certain intensity, as well as the passage of time. To recreate that in writing is a bit more challenging, so we had to shift around, focus on each pilot momentarily before jumping to the next point, and so on. You might also notice that we didn't break Episode 26 up with very many bars- again to help keep that sort of continuity and frantic pace. In "real time", the episode covers perhaps 14 hours, picking up just moments after the end of Episode 25, and going clear through into the night, covering battlegrounds both on Earth and in space. Cutting from one scene to another at a cliffhanger, jumping around... it helps mimic that feeling of witnessing a total melee, with dozens of units all blazing around at once, with little or no order to it. While a lot of the details of the battle are left to the imagination of the reader, we've tried (and with some success apparently) to provide a good jumping off point.
    Episode 26 is nearly as long as 25 (which currently has the dubious honor of being the longest episode to date), but according to Mechmaster, it seemed too short. Rereading the episode myself, I can see why. It took me awhile to read, but it seemed to just fly by. You know what they say about time and having fun =p

    And that about closes this shpiel of mine. I might do another rant about social structure and/or fleet tactics sometime in the future. Stay tuned! ^_~

~Firefury~