Just one extra part.

[Motokid600]

Decouplers with pushers for the times when struts cancel out the separation force.

And.. an air compresser with tanks to fill that can be used for anything. Always welcome more means of propulsion.

[metl]

Hydraulic hinges would be nice. Some way of making doors, ramps, or movable engines.

[Skorpychan]

toilets. Where do the Kerbals... you know, go to the bathroom?

The airlock?

Otherwise, I feel they simply excrete rocket fuels.

[tntristan12]

Engineer Redux part!

[DisarmingBaton5]

A hinge. Just a hinge.

[astropapi1]

Engineer Redux part!

Amen to that!

[barrenwaste]

Well, my first choice would be a hinge, but since so many are all ready talking that and because I think we'll get it soon enough I'll say a small turbojet. Make it half the weight, thrust, and size, and with an equal or better fuel consumption. It would be awesome for ssto platforms and for quick maneuverable vtol and stol platforms.

Edited December 31, 2013 by barrenwaste

[toric5]

i have two things that i think would be cool. (they don't rely on each other, so consider this two posts.)

1. i read a discussion about some sot of electromagnet part. could be used for depris cleanup, maybe mechanics, keeping evas close to the ship, and some creative players may even be able to make rail guns. i think that would be cool, as the concept is simple yet the possibilities are endless. (like the beloved cubic strut.)

2. kerbal engeneer chip. (alctualy, it would be better to integrate it into the pod, or even bake it a flight computer, maybe use the ASAS model?

[davieholgate]

A motorized hinge.

*cough* infernal robotics mod: hinges, docking washers, motorised rotatatrons, etc etc

[EvilotionCR2]

soil scoop for unmanned missions.

[Roastduck]

Right this very minute, a docking port that works both ways. I accidentally put one on backwards, and didn't realize it until I went to add onto the station just now. And it's the only port on the whole first part....

[Lazro]

Mountable camera. For science and taking pictures, etcetera.

[Clockwork_werewolf]

Just a quick note, this is NOT a suggestion thread for the Devs. This is just a hypothetical question out of personal interest. This is also not a mod suggestion thread. I know that about 90% of the things suggested here are included in mods but some people don't use mods. This is really just for interest and to see what people think when limited to one item.

[Brotoro]

Other things I'd like have been suggested already... so I'll go with: Triangular-shaped structural plates. I'd like to see the cool stuff people would build from those.

[JiWint]

A magical part that makes you 10 wishes.

[SpaceSphereOfDeath]

Other things I'd like have been suggested already... so I'll go with: Triangular-shaped structural plates. I'd like to see the cool stuff people would build from those.

Ether this or a strut gun so you can strut your docked ships together

[celem]

Programmable Logic Gates. I always wanted my ship to actually read the data from sci instruments and be able to trigger a staging event or action group at a given threshold. (i.e. read the barometer, trigger chutes at X). The ability to include a concept such as 'if' into our ship's parts.

P.S. Implement it like RSD and I keeell you!

Single part I already use that I couldnt do without would ofc be the KER chip.

[bsalis]

Powered hinge.

I don't foresee any mechanical parts though.

[Tuareg]

flexible connection for refueling...

[TMS]

Hinge or ball socket.

[AceGamer]

Fairings or cargo bays with working doors.

[Commissioner Tadpole]

Rockomax tricoupler.

Because single rockomax parts are not enough.

[Pwnstarr]

Surface sample probe / scoop (a multifunction part?)

[Nightstar]

A lot of cool parts...

But a small parachute the size of one Kerbal would be nice. A last ditch so to speak...

[harald705]

You can actually put a quad-coupler and four small atomic engines.