MEMs are less than 100 um features and smaller. It is usually about repeating a pattern like a microchip in lithography.
Electrodes vary from machine to machine, but I would say they are macroscopic objects (>1 mm). At the ~2MA level the anodes tends to be 5-10 cm in diameter with lengths over 20 cm in some cases. It is perfect territory for CNC and other approaches. 3D printing might make it easier to install cooling channels and other features in an anode that are difficult to do with conventional machining.
I’ve been told for tungsten MEMS techniques that molds are sometimes used to hold the powder in place. It is a two step process. A plastic-type material comes out of a 3D printer. The powder is poured in and a laser is used to locally melt the tungsten around the mold in a way that doesn’t damage the mold. Powder can be added as the process moves forward in a layer by layer approach to add more material. The second step is like 3D printing but I’m not sure it is technically 3D printing.
If “highly packed powder” is used, it probably means 80% of theoretical density. Typical tungsten vendors like McMaster-Carr sell rods at ~80% theoretical density.