Check out DICA pads. I researched a lot and really didn't want wood for maintenance, splinters, etc. wanted pass big enough that would at least double the size of jack pad in case I was off a bit on where I placed them.
Found the DICAs and these particular ones were like 160 each! Found guy on eBay selling a bunch of them and got a set of 4 for 150. These things have handles and are the bomb. Their load rating is more than they would ever see and they will last a lifetime and then some...so solidly built and large enough I haven't missed yet.
Yes, there are cheaper ones or you can build but buy one good set and good.