When I was brainstorming what to do with the tobacco that I grew, I considered pressing plugs. I have access to all of my metalworking tools, such as a ten ton hydraulic press, metal frames, etc... But, then I wasn't sure how I was going to store the plugs. I could make large ones, but... large jars? or small ones that could fit into a jar, but I hate cutting small plugs into small little flakes. So, I found hundreds of videos by tobacco farmers showing how their families had twisted tobacco to roll them and press them for hundreds of years. And, twists were easier to pack into jars.
If you are wanting to save space, think ahead to how you will save the plugs once pressed. However, if you just want to save space by packing more tobacco tighter into jars, Woods made this excellent post a while back... http://pipesmagazine.com/forums/topic/the-tobacco-press-that-you-already-own
But, for me and how I smoke, I don't like opening jars and smoking out of them for long period of time. When I pop a tin or a jar, I want to have it completely smoked by the end of the week. So, couple of ounces in a small jar works best for me. YMMV