First take a punch or nail and make an indent. Then use no larger than an 1/8″ drill bit. You can easily enlarge hole once your thru. Two things; Make sure your drill has enough rpm’s. If your using a battery powered drill, sometimes the less expensive ones don’t have enough power. If this is the case, see if you can borrow an electric drill for this task. The second is make sure your drill bit is sharp. It’s probably best to go to the store and buy a new one. They should be about $3.00 for a package of two. I don’t see any reason to buy an expensive drill bit. I have built this cart and most of these stoves do not have extremely thick SS. One more thing, this job is easier if you have a variable speed drill, starting slow to set bit and then using higher speed to punch through. Good Luck.