Side Hustle while at work

I'm looking for a side hustle to do during downtime at work. Ideally, I would like to bring in around 500-1k per month. In my current job, I probably have around 2-3 hours of downtime in my 8 hour day, broken up into 30-45 minute increments. I will be switching locations soon and I think I will have even more. I would love to find something to do during this time.