So charleans here, heads up, had a lot of work to do with work from home, so didn't have much time to play / work on the customize-able mk4.
Was looking over other mods and i love the NESTT mods or base builders etc, i wanted to test and try to see if i can add one to the spidertron, i might work on it as a separate mod so it doesn't affect this one (though by the time i can finally get something working i'm worried that someone else might make one working before me), but i'll work on this after i finish with the mk4 one.
Don't forget if there is a need for fixes or compatibility i will always prioritize those (since they are easier :D ).

Ah, to late to make nesting for it now, someone else made something: https://mods.factorio.com/mod/Spiderissmo , to be honest i bet he did it better than i could ever make it.
Was also thinking instead of working on the mk4 i might just put more settings for the current mk2, mk3, like health selection, damage types reduction etc. , but barely got any time, i made 2 other simple mods like 2 days ago.

Added 0.3.0, cough finally did something and didn't lazy around this weekend.
Changes for 0.3.0, you can also find them in the changelog but here is again:
- Added proper layering for the eye color changing.
- Fixed a bug where there weren't any dust when moving the legs.
- Some refactoring for the compatibility files.
- Some fixes with dealt with it mod not really working properly when settings vanilla spidertron sizes.
- Tried to make the code more MP safe as suggested by billbo99.
- Added configurable health and inventory size for MK2, MK3 and ghost weaver, change-able from the mod settings.
- Added Healing-ray for the Ghost Weaver with mod setting to change heal value.
- Added Reaping-ray to the Ghost Weaver, with mod setting to disable it.
- Ghost Weaver got a new turret on his head, sorry about the laser offset, got no idea how to move it around with the head movement.

I still feel bad i don't know how to work on that offset, Resarium suggested looking over how the turret does it and indeed i need to look over that.
The healing ray idea was freaking awesome idea, thanks @billbo99 , it took me a bit of trail and error to understand that the damage value was in the beam itself and not the ammo or gun.
We finally worked on adding layers for the eyes, that means the body can be colored properly again, though the new turret is not color-able since we are not sure what makes it color-able, could be the body mask but we need to check / test it.
We literally worked on the healing ray and reaping ray today only, so it's not really fully complete, we wanted to add 2 turrets on the weaver head but we couldn't properly center it, we didn't have enough time either since tomorrow back to work

Don't be shy on giving any feedback or bugs / errors.