As far as I know there are different versions to install of SketchUp. One of them is free - and doesn't become obsolete after 30 days. Personally I haven't yet had the need for the paid version. Once I got the hang of it - SketchUp has become my fav tool of anything I want to - or need to - build.
When making a console - make sure you dl ready made models to incorporate into your own project. There's no need of designing an AGO pedal board from scratch. You simply copy a reliable one from the web.. check the measurements and incorporate the parts you need from it into your own console model. The same goes for keyboards. Make use of all the online time saving resources you can get your hands on.
When I started my current project of making volume/crescendo pedals - I discovered a model of the midiworks.ca type - decided for those measurements and copied it into my working project. Many serious manufacturers have models of their stuff available online for SketchUp - in addition you can use parts of what other users of the software have shared.
OK - not all special parts are available... - my already bought toe pistons was not available online - so I drew an accurate model of one - and voila (!).. copy/paste the number I needed (10) and so on.. - i.e. do some planning - hack your design into parts, make separate files and copy them into the main project file. You will never look back.
With ScetchUp you can do accurate modeling.. down to the 000000.1 - it lets you decide how accurate you want your project to be. There's stuff to learn - but you will never go back to pen and paper again.
Although I'd very much would like to see pictures of a foam project I think digital 3D-modeling will win easily against any such project.