If you don’t have one of those automatic ice maker fridge, you can still have a homemade ice factory right at your hands

First, make sure you have to wash and clean your ice trays.

Since these trays will be stacked, make sure the bottom of the trays is not contacting any dirty surface area to prevent it from picking up some dirt while stacking on top of another ice tray (bottom surface area contacting with the water, eventual ice).

One simple strategy is to find a flat area like in a clean dish rack. Then after washing them, you can stack each tray, bottom faced up (reverse), as you are putting them away.

Then, when you are ready to put in the water for ice making, just flip one ice tray at a time and start to fill the water (careful, pulling water gently through the ice tray ridge groove to avoid splashing).  And as you fill up a tray, go to the next, fill that one too then stack it up on the previous filled ice tray. Once you have stacked a pile to the right height fitting your freezer space then place it into your freeze then repeat rest to finish.

There we go, an ice clean factory that you can do without hassle!