This technology was reported for student use at Pomona College back in 2005:
The cost of the setup was in excess of $5000 due to the use of a consumer grade DLP projector (which are still pricey) and a lab grade trinocular microscope. The article claims even an ordinary stereo microscope can be used for less demanding applications. I haven't taken a look, but I'll bet the name(s) of one or more of the principals presenting the above paper are on one or more patents that are held by Maskless Lithography Corporation.
I hope there are talented folks in this group who might start thinking about putting together a DLP system on a hobbyist's budget. Up until now, the only hobby systems, presented in this group, not requiring some sort of mask, e.g led/laser flat or cylinder photoplotters have been built by individuals with machine shops at home.