I love this mod!

Yet, the mechanoids were never originally designed for colony use or cooperation with pawns. Here are 14 functional module/operation designs and 5 cosmetic ones that improve weaknesses in the mod/design of the mechanoids. Note they all use vanilla resources, like bionics and charge rifles as ingredients.

Functional Modules:
1) An "overdrive module" to speed up centipedes (or any mech)? The centipede are soooo sloooow and they barely engage before tribals reach the walls or pirate mortars start flying. Can we have an overdrive module that consumes internal battery power for speed? (It would mitigate how most modules, like the battery, already slow down mechs). Also, this would make the centipede a little more worthwhile as a Giddy-up tank. I suggest it costing chemfuel/neutroamine/uranium/beer/wort (it's like a "nitro booster"). I suggest a stronger 2nd option which uses launch pod tech to strap boosters onto the mech - perhaps requiring 2 triple rocket launchers to make a "jetpack module." This is, by far, the biggest problem with the original centipede design - a colony needs faster mechs for defense. The centipede needs to be convertible from its heavy assault gun role into that of a far more useful medium tank.
2) An "overcharge module" for +25% firing speed at the expense of battery? The recipe costs a charge rifle along with mech parts. It might require charge weapons tech?
3) An "overload module" for more carrying capacity (like saddle bags) at the expense of speed or battery? This would make the centipedes more viable for caravan use. It would cost either leathers (for saddle bags) or steel (to retrofit trunk capacity). I thought of removing body parts to create "trunk space" but I'm not sure if that's complicated to mod in (maybe a hediff that increase carrying and reduces armor?). If its possible to "strip" a mech of its weapons and armor to turn it into a logistics truck - that would be awesome. Imagine stripping a scyther down to make it super fast so colonists can ride them like light cavalry!
4) An "optical module" for +10% aim? The recipe cost a sniper rifle and a bionic eye (i.e. it's a scope with an eye inside it).
5) A "Thrumbo horn module": can we mount a thrumbo horn to, say, a scyther's head for +5 melee? Maybe paint it red so it can RP as a Red Zaku? Centipede also deserve horns.
6) Extra Power claw module? Recipe: bionic arm + power claw = extra scyther arm for +50% melee attack speed.
6) An "Anti-grain module": it's like the bigger cousin of the self-destruct module. Recipe is the same as the self-destruct module, except with an anti-grain warhead. Relying on a mortar is too inaccurate, so sending in a single scyther with this is much more effective.
7) "Bionic/Archotech Legs module" can the centipede have extra bionic legs for +10% move speed each? It's so damn slow!

Specialized modules and alternatives to turrets:
8) "Mount Psychic emanator": carries the mood booster into battle in replacement of a turret?
9) "Mount Comm beacon": I have no idea how to program this as a context menu, but it's a mobile "comm console" option on the mech by installing a trade beacon instead of turret. It's basically a mobile comm console useful on new maps and when attacking. This might be needlessly complicated, but maybe it would allow faction calling for pawns in a caravan? Often, some of the best social are the traders and so its useful if these pawns can call people in the field. This would make their social skills useful even if they haven't returned to base.
10) "Mount Stretcher": At the cost of meds and a medical bed, it functions as a bedroll during caravaning and allows rescuing/carrying incapacitated pawns in battle. It replaces the turret. I'm not sure if this is viable, but it would be great if it can be used to imprison enemies in the field as well. Maybe a context menu command for downed enemies, which straps the pawn onto the mech?
11) "Mount Trojan Horse": Basically a super giddy-up module costing 4 times more, allowing large mechanoids to carry 4 soldiers in/out of battle in an armoured cage. I was hoping this would synergize with the belt module and the "overdrive module" from above, so the a centipede could become an armoured car delivering brawlers/boomalopes into battle. The Mammoth from More Mechanoids would also be a good chassis if it had a means to move faster - at worst it makes a great battery ram.
12) "Mount surgical arm": it's a big syringe on an arm. It's like a repair arm for humans that injects meds, go-juice and, maybe, nanomachines. It would allow mechs to very poorly tend humans (medical 3).
13) "Mount improvised armour": basically plaster it with more plasteel - maybe paint it red. If it can somehow act as a mobile shield, with a cover bonus, that would be a bonus. It's an option to make the mechanoid even tankier (and probably the least useful module, since mechanoids are already very tanky)
14) "Strip parts": basically an operation to remove armour/weight for speed. It's a poor mans alternative to speeding up mechanoids and also gains 5 mech parts. It would be a hediff with +10 move speed, but -10 manipulation/hearing. Naturally a reverse operation could remove this.

Cosmetic modules (so your mech are distinguishable):
A) "Battle banner module": a cheap little devilstrand flags (cost 5 wood and 5 devilstrand/fabric)? It would make a colony mech cosmetically distinguishable in battle from hostile ones (especially if the mech has no turrets installed). I was picturing either a "Sashimono" style banner on the back of a scyther or a "carpet" on a centipede like they put on war elephants.
B) "Paint Job": basically the ability to reskin the mechs so they are more distinguishable in battle/from each other. At the very least, can we paint at least one of them red with the blood of our enemies?
C) "Bones of our enemies module": for the cost of 5 dessicated corpses, your mech can be tribal in the most classic fear inducing sense by drapping skulls banners. It's purely cosmetic and kind of horrifying, but finally centipedes will look like they behave.
D) "Horns Helm" - basically give your scythers that Teutonic knight look. Centipedes can have them too, for the cost of 2 tusks. Maybe it should give +2melee.
E) "Heart module": even centipedes can have a heart - literally! This is purely for RP, but maybe the mechs can form a bond with that reclusive hacker who dresses in black cause his social skill is 0 and he's staggeringly ugly. Maybe said hacker convinced themselves its a friendly Tachikoma while painting it blue and dressing like Batou from Ghost in the Shell. At worst it can give +5 fluid reprocessing.

Other balance comments:

After trying out the mod, the greatest balance weakness was the original design of centipedes. They crawl slowly into battle because they are heavy assault units meant to burn down colonies. They are meant to fight in a group and get their mobility by drop pod. Yet, for colony use they need to be made much more flexible, since most of the time they fulfill defensive needs. What use is a heavy tank that's so slow and energy efficient if it never arrives to battle when and where counts? I'd rather use up more battery so the centipede can get in position and fight outside the colony, even if they will run out of energy doing it. As it stands, tribals are burning crops and bashing down doors before the mechs arrive. It's especially bad if the Rogue AI is deep inside the colony (for protection), as the centipedes have to crawl even further to meet the enemy. If there's a module that's badly needed, it's one that gives the centipedes enough speed to get them out of buildings/urban combat.

Before writing these suggestions, I tried to mitigate the travel time by placing charging stations close to the front lines all around the map (in bunkers), but the mechs choose the closest stations so I can't always garrison the centipedes at appropriate locations if there are other mech types involved. If mechs could be linked with specific stations that would also help their utility.

All these things aside, I love the mod! There's quite a lot of suggestions and I'm sure not all of them are viable, but I'd really like to see ways to mod the mechs and personalize them for colonies. In my last colony, I captured 26 mechs, but they were basically all walking turrets. I think with better modules it would be more fun to have fewer, high quality custom mech than just having a lot of them. The module idea to begin with is great since mechs can be tailored to fulfill roles which colonists can't.

As to how you want to manage things, if you decide to expand modules, it may also be better if modules are a sub-mod. The whole concept has a lot of potential and you've already done a stellar job!

Well, that's all my thoughts on modules, please feel free to use my ideas as you will! Thanks again for all the great fun you've given us Roolo!

p.s. centipedes deserve Run and Gun integration. They move so slow that they really need to shoot and move.