You can use the Sculpfun S9 laser engraver with free LaserGRBL software which works OK, but it is a little bit clumsy to use. It is great for some tests, but I chose Lightburn instead which is much more capable software, and it is very intuitive to use. It is not free though, but the license costs 60$. But, the software offers 1 month fully functional free trial which will help you decide if it is worth it to you. For me it was definitely worth it because it saves so much time (which is not free).