I don't know of a SketchUp alternative on any platform. There are lots of modelers out there but none are really set up to quickly construct in Imperial dimensions and lay in materials as simply as SketchUp does it. Blender3D works in units, so you have to translate for the ones you want to work in. (A huge problem for us foot-inch-fraction users!) And it obviously lacks the interface and orthogonal control fluency needed for furniture/architecture and without all the unrelated animation overhead. There are loads of others, but I've never found anything mature enough useful for woodworking. My Wine setup in Fedora broke years ago when they re-hashed the graphics drivers and I decided to stick to Windows. Now I also use a Maxwell plugin for rendering, so Linux/Wine/SketchUp is simply not an option for me.
As for Linux and CAD, I don't know of any pro solutions cheaper than AutoCAD LT on Windows:
- ARCAD is mature, but it looks like the full version is €2,185 + VAT.
- BricsCAD is mature, but it's $1,000 to get to 3D.
- FreeCAD boasts some nice screenshots and is built on the Open CASCADE platform.
- CYCAS has been a sharp looking software around for a long time, but it doesn't look like it has been updated in 3 years.
- DraftSight is "free as in beer" right now with somewhat limited functionality.
I occasionally run across others but am shortly disappointed to find them abandoned, exorbitantly priced, or missing some very basic functionality (like printing or DWG compatibility).
Just to be clear for anyone else reading along, CAD and 3D modeling are two different things. Shop drawings are most useful in 2D CAD, where you can emphasize lineweights, show very detailed dimension structures, and clarify material types. Frankly, if you don't care about pro-level CAD, you should invest in a manual drafting table with parallel bar and some pens because it is going to be just as fast at a considerable discount.
Design is useful with 3D capabilities, where complex and accurate visual qualities (like perspective, materials, light) can be observed almost real time. Modelers tend to make it easy for animators and film makers to represent reality. Most people don't realize this, but nearly 100% of all car commercials and advertising images these days are actually virtual 3D models! (There is currently a truck commercial running where a sunny field is reflected in the chrome bumper of a truck driving in a city in a pouring rainstorm.)
Doing both 2D CAD and 3D modeling? That's what BIM is supposed to be. Unfortunately, even these $5k packages don't do either very well. Theoretically, BIM lets you do both at the same time, but I find it takes longer to build and doesn't represent 2D as well as CAD. But your mileage may vary.
I'd pay for a FOSS solution for Linux that solves both my 3D and my CAD needs. But since I started maintaining a reference lists online of prospects in 2002-ish, I've still never come across anything. (If Blender3D would only add a real-world scaling system capable of Imperial inputs, we might get close!)