Construction question: closed loops

[Vkihyone]

Is it possible to join parts into a closed loop? i.e. taking 4 micro nodes and 4 cubic octagonal struts and forming a closed cube.

Edited August 3, 2015 by Vkihyone
question answered

[InterCity]

Not really, a part can only attach to one point. You need to do it using struts, and with the offset gizmo you can make it look like a closed tube.

[Red Iron Crown]

A strut or docking port pair is necessary to make the last connection in the loop.

[Snark]

Just to expand on what the previous posters have said: KSP models a spacecraft as a "tree": that is, every part has one (and only one) "parent" part that it's attached to. Multiple children can be attached to one parent, but you can't have multiple parents of one child. The "ultimate" node is the root part, which is the first one you create when you're in the editor.

The fact that it models craft as trees means that closed loops are simply impossible. The only way to kind-of-sort-of get around this is to follow Red Iron Crown's advice-- a strut can connect any two parts, and docking ports can dock however they like (not subject to the tree restriction), though of course then you have the disadvantage of not having a truly solid connection.

[ajburges]

Note:

Docking ports won't actually connect until you load the craft. This can cause issues from either misalignment of the force of gravity. A strut is often your best choice unless you are assembling in orbit.

Relevant terms to search for are "torus" and "habitation ring". Ring segments are a common feature of stations, so look at some of those.