I would like to know what are the things I have to factor in when making such kind of a rocket. For example, material type, calculus, local laws, and regulations etcetera. Your responses are highly appreciated.
When you say "calculus" I assume you mean advanced mathematics and the physics topics such as fluid dynamics that the math would support. Surprisingly, you probably don't need that. You would need that if you were reinventing all of the technology, but you're not. You can learn most of what you need as a craft, learning the materials and techniques needed from others who've come before.
The problem is that, when it comes to reaching the Karman line, there are precious few amateurs who've ever come before. Learn from others in high power rocketry. There's no shortage of people who've gone a kilometer or two high, there are a good number who've gone 5 kilometers, but fewer and fewer who;ve gone 10, 20, or higher. Still, you can learn most of what you need from them.
Also, I don't want to discourage the study of advanced math, fluid dynamics, aerodynamics, chemistry, thermodynamics, etc., etc. If those are the things you want to study then I applaud you. But if what you really want is to throw an object 100 km straight up then you don't actually need to.
Cost? I really can't say for sure but I thought I heard the S motor the CSXT team used was in the neighborhood of $30k - maybe?
I just did a very quick and dirty look at some high end CTI reloads to get a "typical" value of the "price of impulse" in USD/Ns. (Ceseroni Technology Inc., or CTI, is one of the major commercial manufacturers of reloadable high power rocket motors and the propellant loads for them.) Extending what I found out to a mid-range S motor I get about $30,000. (There are no commercial manufacturers of motors for amateur use beyond O motors, and the motor you'll ultimately need will be about 16 time larger.)
And remember,it's not just the cost of the motor for the space shot. It's also the many, many flights building up to it. I'd have to agree with the previous rough estimate of a couple of hundred thousand dollars for propellant alone. The many rockets you'll build (and probably destroy) on the way will cost several tens of thousands more.
None of this is meant to say that you should not go for it. Your first question was "What are the things I need to consider when making a rocket that can hit the Karman line?" and what I'm saying, what most of us are saying, is that the very first thing to consider is that it's really, really hard, really, really expensive, and will take a really, really long time. The CSX team was founded in 1995, had about 30 members, built at least four big, expensive high altitude rockets before the one that successfully passed the Karman line nine years later, and did it with corporate sponsorship.
If, in light of all that, you still want to make the attempt, I wish you success. The next thing you need to consider is that your initial question was too general to elicit any more helpful answers. So instead of answers, I'll offer advice: read, build, read more, build more, read a lot more, build bigger and more, and repeat as necessary. Along the way, ask many, many questions, and make the questions as specific as you can manage so that you can receive specific answers.
