Over the years have had the opportunity to disassemble all of these devices to upgrade or repair them with very few problems.
Biggest suggestion for a new builder is research 2 or 3 times, print the guides your first time and in the case of a iMac 3 hands are always better than 2.
20" iMAC 2.16ghz 3GB / 1.5 TB HDD w/fusion
27" iMAC 2.4ghz i-7 24gb / 240GB SSD 120GB SSD 500GB WD Blue Drive w/ Paralels EMC2390
15" Macbook Pro 2.3 ghz i-7 16gb / 500hdd w/ Parallels
EMC IX-2DL File Server
Apple Time Capsule
HP Laserjet Pro
I am a training specialist by day and a geek by night. I have disassembled almost every electronic in my home at one point or another if to do nothing beyond to remove the accumulated dust and dirt buildup.