Use 3/4"/19mm plywood, and it should be quite strong enough. Make it just barely larger than the base area of the machine set up as you wish. Put runners of hardwood or perhaps metal under the base and bolt through them to fasten the handles to the runners and make the runners, base, and handles one unit. And start lifting weights if you're concerned about your own ability to lift it. You can start with cans of food, graduate to bags of cans, if you don't have access to a proper weight room or weights.
I had to lift my boxed Unimat DB200 the yesterday, and was surprised to find it felt rather heavy. There are a few things in the box that weren't there I when I got it last year, but they're mainly new? bearings and belts. The box minus those items was right at 25 pounds or about 11.3kg a year or so ago when I got it, so I'll be taking my own advice. The moving of furniture and boxes of stuff that I've been doing is apparently not adequate exercise to maintain my own strength.?
Bill in OKC
Bill in OKC too