We already make part out of struts and fuselages as if they're polygons, and Jundroo put planned flag on my suggestion to make grouping or welding parts in designer.
What if we take it as a general way of making parts in SR2?
A part, saying Crew Capsule, is consisted of several parts with realistic and detailed functions: Front Plate, Back Plate, Heatshields, Glasses(transparent!), docking ports, and all the IVA gadgets including seats and sticks. To reduce complexity and annoyance, they come as a single part as if they're welded or grouped - but could be disassembled in several ways.
In several ways I'm thinking of these:
1. Factory Joint: Can only be disassembled in designer, never be in flight without tremendous shock.
2. Field Joint: Can only be disassembled with great heavy-equipment a.k.a. VAB or such.
3. Welded Joint: Not as hard as field joints but not meant to be disassembled in flight.
4. Assembled Joint: Can be disassembled in field with proper tools for maintenance.
5. In-flight Maintenance Joint: Can be disassembled by crews with handheld tools in flight.
6. Driver Joint: Can be disassembled with a screw driver.
7. Plug joint: Can be unplugged casually.
8. Not-actually-a-joint: You can put a photo frame or such on your cabin, right?
Benefit of this is
- You can upgrade your parts in designer like, saying, replacing a thick and massive nozzle bell of your engine or backplate of your cabin with a thinner and lighter one
- You can maintenance your craft in flight and fix it as if Mark Watney did!
- And so on
Wouldn't be much performance-demanding since SR2 already have a awesome function like grouping parts into one to reduce calculation. The whole part would be considered as one group until you disassemble it.
If I'm being more greedy, the joints can have different health points that a tough landing can displace your plugs while your factory joint would survive a massive explosion. This will help reducing calculations, not adding it, since you can ignore all interactions below certain point!
@AnotherFireFox - maybe the penalty curve is flat at that end of the sliders.
But making a joint in a high pressure vessel that carries high loads, and is quickly removable and easy to reassemble... That sounds heavy and expensive.
Cryo tanks tend to be monolithic.