WARNING: DISMANTLING SOMETHING WITH A CRT MONITOR INVOLVES A RISK OF ELECTRICAL SHOCK, DUE TO THE CHARGE STORED IN THE ANODE. If your computer has been off for a long time, then it is probably safe.
This guide is a walk through of the dismantling of the iMac G3, made up of pictures taken during the dismantling process. The pictures are useful for people completely taking apart the iMac who want to see the mechanical joins (mostly hooks) between the different parts, so that the parts can be taken off without breaking.
Step 1: Expose the Motherboard and Remove the Hard Drive
Follow the instructions in this video to expose the motherboard and remove the hard drive.
Step 2: Remove the Logic Board Piece
Unscrew all the screws in the logic board. There are two pieces of the logic board, and you must disconnect the cable between the two pieces to remove the larger one. Remove the larger one first, and then remove the smaller one.
Step 3: Remove the Speakers
This part is difficult to do unless you understand how the blue plastic hooks under the speakers are shaped. You must bend the speaker up and away from the middle of the computer to open up the bottom hook. Then, bend the speaker inwards towards the middle of the computer so that the hook will be released. Pull the speaker horizontally away from the computer to remove it. Repeat with the speaker on the other side. If you would like to take the speakers apart too, you can use a hair dryer to soften up the glue.
Step 4: Remove the Plastic Monitor Frame on the Front Face
To do this, you have to first uncover the two screws on the bottom of the plastic frame. These screws are covered with plastic pieces that can be pried off. Then, you have to unhook the monitor frame from the back blue part, by pushing it down and then out. There's an example video here: https://youtu.be/snkMLQskFi4?t=272
Step 5: Remove the Blue Plastic Housing
Remove the blue plastic housing one side at a time. You will need to pull each side down and out to unhook the blue plastic hooks on the edge.
Step 6: Remove the Underlying Monitor Frame
Unscrew all attached screws and pry off.
Step 7: Take Off the L-shaped Plastic Pieces on the Side
Our L-shaped plastic pieces were connected to the monitor by means of a taped wire. Rip off the tape on the wire. The pieces of your iMac are now free from each other!
Step 8: Free the Metal Platform From the Monitor
If you are making a project from the disassembled iMac that requires the metal platform, you can take it off by unscrewing all the screws, cutting all the wires, and using a dremel to saw off the plastic screws. If you need a flat platform, you may also need to use your dremel to saw off the metal bits sticking up on the platform.