They are standoff screws I got from Amazon. I also used 3mm lock nuts to secure it so it’ll be less likely to come apart.
https://www.amazon.com/HOBBYMATE-Standoffs-Quadcopter-Building-Motherboard/dp/B01I0SORIE/ref=sr_1_3?ie=UTF8&qid=1531684835&sr=8-3
https://www.amazon.com/Electronics-Salon-100pcs-Metric-Black-Hexagonal/dp/B0129BDGW6/ref=sr_1_8?s=hi&ie=UTF8&qid=1531684914&sr=1-8