I figured. A module with a beam expander is just what you need. You could probably get away with a 10x expander. That would give you a 15mm beam or so at the aperture, and a 20mm beam by the time you get to ~50m out.
You want something that's going to stay relatively stable, is well-heatsinked, and will stay in TEM00 generally.
The device you linked is purpose-built for firearms and is self-contained and gun mountable. The cost and effort involved in building something similar is going to add up quick. Make sure you consider that before diving in. ><