There was a stray cat came over to my place (kampung house) years ago so I just let her stay.
Now there's even more of them.

Never caged those cats, just let them roam freely outdoor.
But because it's kampung area there always the occurrence of them gone missing, ate by snake (REALLY), fight with other strays, etc
The grown up ones aren't a problem, it's the small kittens - they just loves to crawl into car engines.

I just made a 2' x 5' x 2.5' height decently large cage but obviously none of them likes being in a cage.
Decide to just DIY as those ready made products are freaking tiny for their price.
Is there method to make them want to stay in cage, or at least not resisting it that much?
Is there somekind of heating product that don't require electricity to put inside cage? They loves to get into/onto vehicles becuase of the residue heat after all.