You have an idea. You want to build a shuttle. Make the orbiter first. If you need design cues, head to the NASA website or Wikipedia and stare at photos. That's what I do.
When i built Concorde on KSP, I didn't look at other designs on KSP. Cos I'm not building someone elses Concorde, I built my Concorde.
I literally spent 2 days (and nights) just searching for photos of it from all angles, wheels down, wheels up, nose down, nose up, in flight (there's only 2 photos in existence of a supersonic Concorde, taken by an RAF Panavia Tornado that was being over-taken at 'low' level. None exist of Concorde at 66,000ft doing mach 2, as nothing else could get alongside to take the photo.) engine intake designs on the RR olympus engines, landing gear placement, dimensions, thrust ratings, fuel tank locations cut-away diagrams. I read up on flight characteristics, landing patterns, fuel ranges, trim designs, anecdotes and stories.
I could give you many ideas for a STS type shuttle. Hell I've got one of my own, Excaliber and has a proper launch tower. But if i built you one, it wouldn't be yours and you wouldn't value it.
I spent weeks making Excaliber work, it's the second hardest project i completed in SFS, as proper shuttles are one of the most difficult thing you can build and because of that, it's one thing I'm actually rather proud of making work. I'm in the middle of uprating it, but I'm hamstrung with thrust issues at the moment on the external tank.
Make one for yourself, and you'll get what i mean when it finally fucking flies straight.
All you need is a pointy bit at the front, a tail at the back, payload area in the middle and an external tank/booster on one side to propel it. It can be as big or as small as you like, powered by whatever you want and lift any payload you desire.
Build it, test it, re-build it, fly it, deliver a payload, land it, take the photos, send it in to TtTOtW and he'll invite you into Shuttle City where it'll join the largest gathering of Shuttles in the community at an enormous Space Station orbiting the moon.
Cheats used to demonstrate.