A man after my own heart. Mine is also a cobbled together contraption, made of scrap wood. At the moment it's just a pillar, lever arm and presser but I'm going to make it a parallelogram like yours. As is I have to be extremely careful about getting it lined up so presser is pure vertical or it tends to spit the cheese out, usually halfway through pressing.
A couple notes for anyone wanting to follow this example:
Don't skimp on the wood parts. Notice that Dave used 2x4s. You need to be sure that the wood is up to the load. If you want to make it more svelte, use oak or similar hardwood 1x3 or a bit wider. At that width it is usually solid wood, but avoid any boards made up of multiple small pieces. I hang 55 pound dumbbells on my 3:1 arm without problems if I keep things lined up. A pine 1x3 would likely split at the bolt holes.
Use plenty of fasteners on the post to the base. The lever is trying to pull it up, and if not quite vertical it will be subject to forces trying to bend it sideways.