How do I build a time machine

Or an alternate reality machine?

I want to go to Middle Earth.

To get to Middle Earth I always just drive to Northern Earth and then turn south and keep going until just past the detour sign then park on the lot off to the left.

You must specify whether you wish to build an electronic time machine or a mechanical, manually operated time machine. Also you need to make up your mind. Are we talking a reality machine or a time machine.

Attach a bike to a big clock so hen you get on and peddle the clock goes backwards, when you get off you will be back in time proportional to how far you've spun the clock back.

I broke mine some years ago and haven't found a way to make it work since.
Nothing is impossible, but you ask for it.

Middle Earth? Go out in the woods with some friends, state your purpose, then eat some mushrooms. Oh yes....