How to build my own huge aquarium?

I would not diy something that large as mine first diy. Experience is most important factor and if you do not have any with building tanks you should start and try something smaller. Maybe a sump, refugium, top off water chamber or something else what you will need. - Diy all that first and then go for main tank.
Maybe you can find someone with more knowledge in that field to help you, in any case you will need a pair or two helping hands minimum for handling such large parts.
-If you know someone who weld then a metal stand alone can be made somewise easy and low cost. You do not need more expensive aluminium or even stainless, ordinary full profile bars are strong and resistant when painted.
-But keep in mind that whatever route you take, everything is expensive with such large size, as someone already mention, and do not go into it if you are not truly ready for it. Is not just equipment and eletricity, you need to fill that tank with life and then maintain it, that also take a noticeable amount of time and money.
We are planning on buying or building a house in 6-9 months. I am considering when we move, selling my current 150g setup and setting up a really big tank. Especially if we build, I can dedicate a large wall to it. I have seen some of the custom tanks online and they are very expensive, even for just a 500g. I'm sure it would be cheaper to build a tank myself.. but I'm not sure how or where to start with something like that. I would want to make sure everything was perfect and there was no chance possible for any leaks or anything, and although I would want like, 1000 gallons, I have no idea on what dimensions would be required for this. Also I would want to be able to perform maintainence without getting in the tank. Lol. Just by using tools and all to clean it. I know it is a long ways off but I also know its good to prepare and know what you're doing. Any advice, links, etc would be appreciated.
YouTube has some good videos on building a tank