Most setups like this lean on ground parallels and machined jaws, so a rough wooden block doing duty as a vise spacer is what makes this one catch the eye. A thick rectangular metal bar is clamped horizontally in a milling vise, and the block sits between the workpiece and the vise jaw as the spacer. It looks crude next to the usual hardware, but the targets here are not sub-micron shop-floor numbers either.
The machining itself is orthodox. A vertical milling machine drives the cut, with an end mill or boring tool held in a collet chuck in the spindle. The tool feeds downward into a pre-existing hole in the bar, throwing off metal chips and curled shavings as it goes. Several other evenly spaced circular through-holes already run along the length of the bar, which hints at how repetitive this job is going to be.
The context explains the repetition. The maker is hunting for the best workflow on a multi-setup job: first locate 30 or more plasma cut holes to mill, then use the milled holes to locate plasma cutting of the part edges to within 1mm. On the piece shown, the maker calls the hole tolerance perfectly acceptable and confirms it is within tolerance, with 0.3mm on a caliper mentioned as an acceptable figure.
The open end of the project is production planning. A fixture plate is on the table as a way to run the job, in batches of 5 or 10, but the maker is still working out how to keep that fixture plate from over-penetration, and the machine operator has little experience with probing. Both of those feel like the real hurdles between this single setup and a smooth production run.