As far as safety is concerned there are two points to be observed.
1) Safety goggles with an OD rating for the wavelength of the laser in use must be worn by you and anyone else that may be present.
2) As many materials give off toxic fumes when burned the work area must be well ventilated.
I have not yet figured out how to control the burn marks produced on the surface of the work. Speed of cut has a lot to do with it I think. Possibly reverse one axis to produce a mirror image and then cut from the back of the work ?.
My laser came from Virtual Village, China but I understand that they no longer supply the 150 mW version.
Power supply is a 0 - 30 Volt 2 Amp benchtop PSU with current limiting.
Laser is controlled with Mach3 and I am using vector toolpaths converted to GCode - Z axis is disabled and Z axis DRO scale factor is used to set the dwell time. To turn the laser on and off (between cuts) I am using a shutter controlled by the Z axis direction signal.
This link may be of interest to you:-
http://www.cooperman.talktalk.net/index_files/Page4549.htmThe ebay laser looks good but you may need to add a focusing lens. perhaps you should try and get more details from the supplier.
Nice machine you have there.
Tweakie.