This Quick Grip Replacement Pad is a direct replacement for the Quick Grip brand clamp. It hasn't been tested on the Irwin brand, so chime in if it fits for you. This one is unique in that it has a very tight fit and a securing feature that sandwiches the clamp's foot. Definitely a TPU print, and no support will be needed.

There are two versions, one with a smooth bottom, similar to the stock one. The other version will have a serrated floor for increased grip on clamped item.

The print profiles are tweaked with a wide line to increase strength, but standard widths are ok. However, if you change it, I suggest you keep the density high to resist collapsing the floor of the pad on the clamped item (from too little infill).