There is a german fabrication shop that has a online-tool for ordering stuff like that. You type in the dimensions you want, material, thickness and you directly order it from there. A few days later you have your part in the mail. There is also a check box when you want the corners to be welded (I did not tick that one, I welded the corners myself.) It is like Amazon for the machinist ;-)
After some stunt-rigging, by using a crowbar and a lot wood for jacking, levering and supporting I got the machine in the pan without the help of a crane. When you do something like this, take your time, think trough every step and be carefull. Tipping over a machine tool is pretty easy and no fun:
