Discovering this technique put me on a roll, and I was back to sitting in the yard sunup to sundown happily pounding away and making good progress. As my time in Tucson was coming to an end, however, I was confronted with a shortage of suitable rocks. It became very frustrating to walk around and around all these thousands of rocks in the yard and not being able to find ones big enough, to envelop the voussoir in all dimensions, or solid enough to serve my purposes. I kept thinking, where's Dad; I'm sure he could say, oh, I have a piece of limestone just that shape right over here, and a piece of marble over there. One day, although I had found a beautiful specimen for the keystone with two relatively flat sides meeting at a right angle, I had eight voussoirs and was at a loss what to do for the other two. I began to despair, and noticing my distress, Mom asked me if I was sorry that I had gotten involved in this, and it took me a long time to deny it.
The next day, however, I took a fresh look at two voussoirs that I had worked on but rejected, and decided that the one was not too small, it could work in the structure, and the other, which had cracked at a corner (and with stone, of course, when something breaks off you cannnot put it back), was acceptable too because it would lie flat together in the structure. So I had all my voussoirs. I began to work on the keystone. The first voussoir took two weeks, but now with acquired skills and arm strength, I finished the keystone in only two hours.