I conducted my 1st official test of my homemade pinhole mount @ 600um diameter, using an 18mm diameter ocean optics slit mount and black-out aluminum masking tape. Using an everyday sewing needle which happens to be 0.61mm in diameter I carefully poked the center of the foil I had fashioned over the mount and these are the results, a very nice quite and stable laser beam with very low SNR (signal to noise ratio,) check it out below:

The image above can be zoomed in many times for a precise view of the center hole, very straight forward build on this one.