Welcome to Workshop. We trust that you'll get loads of helpful advice and project inspiration from our clever and creative members.
Do you have a specific product in mind that you want to attach to the cement blocks? A little more detail and perhaps even a photo might help our members provide you more useful advice.
In the meantime, I will tag the ever-helpful @Brad as he often has a quick and easy solution for questions like this.
A couple of clip options for you.
50mm metal posts would be the way I would go and sorry @Jason I don't like the Bunnings post support so I would go with something like this -
Hope that helps.
Many thanks @Brad. Please let me know if you ever want me to pass on feedback to the Bunnings merchandise teams. I am happy to do so and am sure they would appreciate any feedback on how they can improve the range.