Ok long story short:

***
a leak developed in the piping behind the drywall in my bathroom
(underneath) the wall facing the toilet. I had a plumber come in
to the condo apt and smash out three tiles at the bottom to get
welding equiptment in.
*****

I thought about hiring out work to replace the tile (which would
involve two straight/square tiles and one with a hole in it to fit
the cold water shutoff valve

But I would sort of like to leave that hole accessible should more
work EVER need to be done. Is there a substitute for tile other
than what i currently have there (a cardboard covering the hole and
duct tape around it)???

I have heard of "access panels" but dont know where the look or get
these

please advice
thanks