For 5 years around the turn of the Millennium I had an obsession with movie prop replicas. At the time I was a huge Star Wars nut and the urge started with wanting a screen accurate copy of Luke's lightsaber hilt. If you dug around on the net there was some information about the raw materials were used to make this kind of prop and how to find the parts you needed to build your own - this was in the days before you could just order an official, screen accurate prop from Amazon.com - the quest for parts was half the fun.
It turns out there was a large, underground (since the hobby is on the fringe of copyright violation) community of prop enthusiasts. In the end, as official licencing moved in on our geek preserve, the community fractured and viciously fell out with each other. I'm sure it's still out there but it put me off forum communities for a long time - by the time I left people were as rude to each other as big-brother contestants.
But back to the plot. In its hay-day, we shared information with each other including, in many cases, construction plans. Before embarking on any project I used to like to create my own plans and diagrams which I shared via a Geocities site: - they tell us Geocities is going away but you can still get to my old site for the moment.
In those pre-SketchUp days I used a 2D program I got from Office Depot for a few dollars called DeltaCad. It wasn't especially complicated but I got pretty good using it and it took me back to my favorite subject in high-school, long before technical design was something you did on a computer; technical drawing with T-squares and French Curves. I used to enjoy making the plans more than making the props so when I started to play with SketchUp it was only natural that I should model some of these objects. Highly detailed construction plans already existed and it was a fun learning experience to model some of these complex structures using that information.