Yup...You'd be hard pressed to tell the difference between a 'cold cast' concrete brick and a real one with the right dye and aggregate mix. An interchangeable plate with the inscription of your choice at the bottom of the mold can easily be changed.
After machining various stone/aggregate products early on and dealing with grit getting everywhere on my expensive robotic tool - I vowed not to do that again...No matter how good your 'dust' collection is, you just can't keep grit from getting into the gear racks and machine ways. It just isn't worth it - for me anyway. It's one of those, "We can...but should we? Is it really worth the mess and risk?". Something to consider...
-B