This question is too time intensive to get a comprehensive answer for free. It should take more than 10 hours to determine what is patented, whether 'kimkaps' is infringing, and how you could make comparable caps while avoiding infringement.
"What are they expressly patenting?" I haven't looked at the patent, but I would suggest starting by looking at claim 1 in the patent. That claim lays out what the Patent Office agreed the applicant had invented, which no one else may practice. To avoid infringing this claim, you need to omit something from your product that is required by this claim.
I would also consider going to www.uspto.gov and searching on the PAIR system in the patent section for the prosecution history of this patent. Within the prosecution history is a file wrapper that includes all of the documents that led to this patent being issued, saved in pdf form. In there, if you find the Notice of Allowance, you may find that the US Patent Examiner that allowed the patent to issue has described what he found novel about the invention. Avoiding this novelty may allow you to avoid infringing the patent.
If you are not sure if you will infringe by making thes caps, your best bet is to steer clear.
Answered on Sep 10th, 2013 at 3:45 PM