This hack turns an Ikea HOL coffeetable-type piece of furniture
(well, they call it a storage cube) into a side-opening cabinet. (The problem is that, unhacked, the HOL is top-opening so you can't stack them.) I use two stacked together as a printer stand plus as cabinets for my PC and ham radios.
Step 1: Decide which side you want to have fold down
he HOL has two sides (opposite one another) that are potential fold-downs and two that are
not. Choose one.
Step 2: Cut 1/2" off the bottom of the side you want to fold down
Remove the side you want to fold down from the HOL. Cut about 1/2" off the bottom feet of this side. This is necessary because when you fold down the side these feet are going to rotate and cause the whole unit to lift up. You can use a manual saw or a SkilSaw to do this.
Step 3: Trim 1/2" off the internal baseboard
Cut about 1/2" off the internal baseboard inside the HOL. The baseboard is the horizontal, almost-cardboard-like particleboard bottom to the HOL unit. It wants to slip into a slot in the side that you want to use as a fold-down, and that will prevent your desired side from folding down, so you need to trim the baseboard back. Again, normal saw or SkilSaw, or even a table saw, will work fine for this. While you're at it, you might want to cut a hole for power cords in the baseboard if you want to put anything electrical in your new shelf.
Step 4: Mount the folding side
With the baseboard inside the HOL, mount the folding side at the bottom using the two ikea-provided fasteners, just like normal. Don't over-tighten the fasteners. The door will now be able to pivot on these fasteners.
Step 5: Cut a 3/4" x 3/4" x 17" piece of wood
Cut a piece of 3/4" x 3/4" x 17" wood. The 3/4" dimension isn't critical by the 17" dimension needs to snugly fit as described in the next step.