Metal sintering layer-by-layer with DLP
SLS uses a high powered laser to smelt the binder of a ceramic or the metal itself. We are talking about at least a 40 W laser which focuses its power on a circle of about 50 µm. How much power are we talking about with that lowest viable laser for plastic SLS?

$\frac{40\ \text{W}}{\pi \ 62.5\times 10^-9\ \text{m}^2}=640\times 10^6 \frac{\text{W}}{\text{m}²}$

A typical SLA/DLP machine like the Sparkmaker runs on 48 W in total. Assuming that's 40 W for their $55\text{ mm}\times98\text{ mm}=0,00539\text{ m}^2$, so the total projector power of the Sparkmaker is

$\frac{40\ \text{W}}{\pi \ 0,00539\ \text{m}^2}=7.421\times 10^3 \frac{\text{W}}{\text{m}²}$

That's about 5 orders of magnitude too little to smelt a layer in the same time. To get a DLP-like projector doing SLS work, you'd need a light source that runs at about a similar power per square meter - wich would just melt the moment it turns on.