Foreword: Sorry for the poor format (and English). If anyone wants to implement them, I could provide further help on numbers.
For now, once you are good on Electronics/First Aid, CBM becomes OP without any significant drawbacks. Eventually you’ll have 2000+ CBM power capacity and dozens of CBM.
I would suggest that:
[ul][li]Every CBM parts shall have a “volume”, it occupies some space in your body, limiting the numbers of CBM you can install.
Head: 20/20 Eyes: 5/5 Body: 40/40 Left Arm: 15/15 Right Arm: 15/15[/li]
[li]The “capacity” of your body will slightly increase with your First Aid skill, but won’t be too much (maybe 50% at most).[/li]
[li]Some CBMs can only be installed in related body parts:[/li][/ul]
CBM Volume Body Part
Expanded Digestive System 5 Body
Internal Furnace 15 Body
Infrared Vision 3 Eyes
Targeting System 3 Eyes
Fingerhack 3 Either Hand
Power Storage 1 Any Parts
[ul][li]You cannot have several Eye modifications at the same time.[/li]
[li]Power generators CBM occupies a large space, installing more than 2 is almost impossible.[/li]
[li]Power Storage CBM has 1 volume, so player could use it to fill up the “free space”.[/li]
[li]Mutation and CBM could be mutually exclusive, getting both of them would lead to a “debuff” or decrease on CBM performance.
On the other hand, there could be some kind of CBM-friendly mutation, not so powerful but providing a variety of choices.[/li][/ul]
some mutations will probaly even help with cbms, having bigger body will probaly increase space for cbms and increase power consumption of cloak device and pneumatic muscules (but its not big problem because you can stick just more power storages)
and if we have loacalized cbms (arms, head, legs…) we can have cbm damage too, lets say your arms are broken and your pneumatic muscles are broken too turning into failed bionic (what are harder to remove)
Most of the CBMs we have now would not interfere with each other, really* - even the different eye modules could work together fairly easily (assuming they were made to, of course). The main problem I see with the current system is the infinite power storage.
I have some ideas on some of that, but it’s probably larger than belongs in your post, and I need to take some time to write it well.
The main things I could see interfering with each other are the muscle enhancement one and the hydraulic muscles, the armored alloy ones and solar panels*, and the internal furnace**/digestive systems, though I think the two digestive systems could work together OK (assuming they were made properly) - they replace difference parts of the digestive system (one is stomach/small intestine, the other is large intestine/kidneys or bladder or both).
**I actually have a bit of a problem with both of these, anyway, the solar panels one in particular, since it works just fine even when you’re wearing an ANBC suit or power armor, but wouldn’t really be worth having for almost any character if it didn’t.