My idea is you can design your own gateways. It could been done by a third-party company or Uplink. The gateway could be designed with a dedicated software or on the manufacturers site (probably on a dedicated server). Designing with "sets" (see image above) and drag n' drop. I made a little sketch with a manual.

I hope you like it!
(I know it's VERY expensive, but you know, custom stuffs are expensive...)
EDIT: Made a big mistake, I accidentally wrote Slots instead of sets...

Technically, there is a gateway maker already (found here), but it only works for uplink (no RAM or SATA slots (SATA in Onlink 0.2.x and later)) and can be set for any price. Done right, this could make fairly-priced gateways for Onlink.

To add to this idea, perhaps you could export and share your custom made gateways.

Hm... For some reason I think this may have already been suggested.

Now, if it was ingame...

Joke?
I've got a few millions hidden away on my several bank accs ingame ... so get a couple of those mc gateways and a coke light please .

As most custom- gateways do, such an ingame gateway generator would just ruin the game's balance.

Actually, my issue is that it's not terribly easy to make clean.

Its not easy to make clean looking, professional style. Most production games that allow in game modding, really just limit you to a certain set of templates to work on, then sorta placing pieces in places via predecided options.