My thoughts is use the pattern until it falls apart and don't just limit yourself to just personal use, If someone likes something you made from someone else design make one for them and charge a fair price for your time and materials used.
for example i have sold a couple of the Brazos Jack design holsters to a couple of my CAS buddys but I always credit Jim for creating the design and I have no doubt Jim is flattered by me making something for sale from a pattern that he designed, That being said here is where I think Jim would have a big problem with me using his designs and would be blatant copyright infringement on my part Per say would be for me to print off a bunch of copys of his drawn patterns and instruction sheets and sell them to the public and he has every right to file suit against me at that point. when someone designs and sells patterns and instructions they expect those who buy their pattern to make the project from their pattern and also expect some will make these projects to sell publicly.