Create a form (without extensions)

Guys

I've googled around and always when I ask "how can I make a form in Joomla" I get the same answer: "-Use extension X." ; "-No, use extension Y"..

I just want the user to have a link to my form, fill it up and whait until "calculation X" ends, so I can show him the answer. Very simple.

I have no problems with php or development, but I can't find the best way to do this in Joomla. Should I make a new module, component or a plugin? That's it.

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