I've been giving this a lot of thought lately myself--definitely a timely thread.
First, I want to say how impressed I am with TD's Caldera Cones. I had a tough time talking myself out of a JetBoil Sol Ti, but once I saw (and understood) the Caldera Cone system, I no longer wanted another canister stove. The design is simple, elegant, and a much more responsible use of resources. It's also (relatively) fast and reliable. While I haven't bought one yet, I've got my eye on an Evernew 900mL pot and either the Ti-Tri or the traditional system with esbit stand. As far as I'm concerned, they have earned the patents on their system and deserve a lot of business because of that.
All that said above, I do want to add a couple of relevant points that haven't gotten the attention they deserve yet in this thread.
One of the reasons that I think people are responding strongly to UM and others like Captain Paranoia making Caldera-type clones is the nature of the cottage industry. Rand & Co. are active here on the forums, and--by all accounts that I've seen--they make an excellent, reliable product and are readily available to help. They even go out of their way to make things like the Fissure which takes far more labor and attention for (what I'm guessing) is only a marginal increase in profit. I have yet to see any bad press about their customer service, communication, or products. They're a small, cottage company that knows the BPL community well and that the BPL community knows well.
In other words, if someone figured out a relatively easy way to make a NeoAir-like pad from readily available materials and then posted that method on the forums for others, our reactions would be very different. (This isn't a perfect analogy. Obviously, the NeoAir is a far more complicated product to produce than the Caldera Cone system. Though, I don't see degree of technical ability as relevant to my argument.) Therm-a-Rest is a big company, and it's owned by the even larger Cascade Designs, who owns MSR, Platypus, and other major players in the outdoor industry. First off, any hit to their bottom line by MYOG NeoAirs will probably be minimal. Even if it were wildly popular on BPL, Whiteblaze, Outdoors Magic, etc. the few who make rather than buy will be much smaller as a percentage compared to Trail Designs.
To add to that, while I've also heard of several excellent reports on TAR's customer service and availability, we don't know them like we know the Trail Designs Crew. We're not as personally invested in their development as a business. Like I said, we just don't know them, and our interaction here on the forums with the real players at TD (versus some customer service rep on the phone or by email at TAR) really means something--personally and commercially. It's immensely satisfying to use something on the trail built by someone you feel you know and whose care and attention to detail you don't doubt.
This connection between between business and customer makes them both people again (a more classical model of capitalism, versus the impersonal megacapitalism that emerged from the Industrial Revolution). I think it's admirable and a big part of why I want to purchase from Trail Designs in the future.
I think the other thing that has been missed in the discussion so far is that the cone itself is not really what Trail Designs is selling. What they offer is the whole Caldera Cone system--the 12-10 stove comes bundled with each of their cones. The stove itself is designed for exactly the conditions which the cone creates--high heat, low oxygen. Not only that, but it is has become the benchmark for alcohol stove efficiency. Take away the cone, and that drops dramatically. Or as Rand has pointed out on other threads, using another stove with the Caldera Cone isn't going to work nearly as well either. (If I remember correctly, he said it more strongly than that--no other stove will work well at all.) The 12-10 stove is an essential part of the simplicity and reliability of the Caldera Cone.
So when it comes to making your own cone, I don't see the moral problem (the legality of patent laws is beyond me, so I'll leave that for others to comment on). The cone is a basic geometric shape, and while it is innovative and creative to use the cone as TD does (and clearly patent-worthy), making one for your own personal use shouldn't be considered a moral failure. Frankly, all the skills you would need to make a basic cone are taught in freshman geometry. And any student with above-average intelligence, a formula chart, and a decent calculator ought to be able to do it well before that. Of course, to make one functional, you'd need some understanding of wind and oxygen flow that are easily gained again in high school, through trial and error, or on the trail (of course, others more knowledgeable could help you out, too). Taking that into account, I just don't see how making your own cone is so wrong--especially when you also consider that you haven't replicated the Caldera Cone system, just its most basic geometrical aspect.
As for Captain Paranoia's postscript, I think the issue is a little less clear, but not much. You measure your pot, input the numbers, and it generates a template for a cone template that you can print out. Basically, it does all that 9th grade math for you. My TI-83 Plus in high school could have done that. Sure, it adds an option to do a Fissure-like cone, but again, that's cutting a cone in half (basic math) and adding some tabs. The joint pattern is different and based on common knowledge, and the venting holes are different. It does leave a space for your pots handles very much like the Caldera Cone, but an average freshman could make that modification to a cone with nothing more than a ruler and some scissors. In other words, CP's postscript does nothing that a reasonably intelligent person with a freshman-level education couldn't do given more time (and some error). That doesn't meet the minimum requirements for infringement on intellectual property, in my humble opinion.
All that being said, if CP offered a set of instructions for building your own 12-10 with the cone, I could see that being a much more salient issue. As it stands, he's only duplicated the most basic part of the CC system, all of which stands well within the realm of common knowledge.
I will say, though, that I'm not a fan of the name "Caldera Clone." For one, it clearly takes the Caldera trademark, using Trail Designs' intellectual property to garner notice. Second, it unnecessarily muddies the waters. Caldera doesn't own the geometric shape of the cone, and CP offers nothing that isn't already in the public domain.
Like I said, I love what Trail Designs has created, and I look forward to purchasing their set-up some time in the (hopefully near) future. They are an excellent company, and I'm glad to support them because of their products and their personal connection. But I see no problem with others making their own cones or using Captain Paranoia's postscript. Personally, full disclosure, I also plan on making a making a cone for my Foster's can pot with help from CP postscript. I'm looking forward to the learning process of designing and testing different stoves for it. It's one more step toward my goal of taking a trip with only (or almost only) gear I made myself.
/*/Edited for clarity and grammar/*/