It's not so bad or difficult, but it consumes time which only makes it practical for a hobby-ist (? ) or for those dying to build a piece of interest.
also check out
www.midibox.org
DIY midi controllers and more ( SIDbox )
http://recording.org/users/kev/
This guy is diy god, lemme break it down;
Neve BA283 ( 1272/1290/1066 ) Mic Pre-amp,
API 312 Pre amp
1081 Mic Pre amp/eq
Universal Audio 1176 Fet peak limiting amp
Teletronix LA2/LA2A Tube Compressor AND T4 module
Teletronix LA4 Opto comp ( single ) in fact, same as La2 but uses Op-amps instead of tubes.
Pultec EQ
SSL bus compressor ( racked )
Consider these items topnotch studio gear, in most cases stationary in all 7 figure studios. Also a lot cheaper than the originals plus the extra mods they put in to improve the original. Both sites take a lot of reading, but any noob can do this as the guides are made for dummies.
Besides this, reading through these 2 sites ( and understanding it ) can tell you a great deal about various issues on mastering/engineering. On the real, knowing this is a big addition to your producing perspective and capabilities. Building such an items is the best way to learn, so if anyone serious about their future in music and still feel noob on technical issues, read and build something from these sites and gain this knowledge.
Like I said befor, both sites are extremely well put together ( for dummies ) and anything you need to know is on the pages, there are loads of pics used to show noobs how its been done. PCB layouts, partlists ( and where to order ), schematics and tips from builders are all there and best of all, free for download.
Cheers