The OX
I first encountered the OX CNC machine at my makerspace when one of the makers was offering pre-cut metal kits for it. I jumped on the opportunity after I had a chance to do a little research. The OX is an open source, heavier-duty machine that you can find on the OpenBuilds site at https://openbuilds.com/builds/ox-metal-cnc-router-mill.3681/. The Thingiverse site for this machine is at https://www.thingiverse.com/thing:1660320.
As machines go, this one cries out for ballscrews (or heavier-duty leadscrews) very loudly. It is large, heavy, and meant for serious work, such as milling harder materials. Mine has a half-horsepower table router motor as the spindle from DeWalt, but if you decide to build one of these, you can use whatever takes your fancy. If your 3018 is up for the job, use it to cut the carriage pieces for you, or grab the drawings and either hand-make them or send them out for fabrication. There are some parts that need to be 3D-printed, and the brackets holding...