Yes, you can. I make the sway bar bushings that way. However, it's not cheap or easy. You have to buy a bushing to get measurements (I don't cast directly from an OEM one, because both the mold silicone and polyurethane castings shrink, so you have to compensate), as well as get a vacuum degassing setup and pressure casting chamber. The material costs (only) for something this size are probably about $75-120 for silicone mold rubber, and $15-25 per bushing (including color dye and UV inhibitors). You can cut corners if you're on a budget, but the castings aren't nice/right (e.g. small fitment issues that require trimming each by hand or muscling them to fit, crude aesthetics, bubbles and imperfections that can create stress points that fail sooner, no expensive UV inhibitors but they will break down outdoors sooner, etc.). And then, after all that, you have to do it a second time for the other bushing of the top/bottom pair.
I've been "working on" some cab mount bushings, for longer than I'm proud of. We were preparing to move, then moved last year, and am now stuck in a rental house without a good shop until my new house is built (which is seeing all sorts of delays because of the pandemic). I finally got all my molding/casting stuff set back up a couple months ago, and I'm hoping to have them soon, though.