Yes, Liro. I am using PDMS for both layers and the hard layer is 1:5 dilution of PDMS to curing Agent. Do you use your chips for cells? do you go straight with tubing into the chip? i want to test that method. Can you share your protocol if you use this for cell culture/cell experiments?

thank you in advance

different diameter punchers are available for punching PDMS layer. you can check the following link >  https://www.tedpella.com/histo_html/harris-punches.htm  for such puncher. We are using it for last few years, it works perfectly. 

Kiiski, what Kind of polymers do you usually use for human cell culture, if you do this routinely? is there any material that is a to-go in your lab ? (that is not hard to handle, etc. so that maybe eventually i can try it as well)