Ed Hayes wrote:
If have 2 feral cats in our yard which we feed and take care of.
Over the last year we actually can now touch and play with them but
they will not come in the house. They truly are wild.
This winter I would like to build them a place where they can stay
which will keep them relatively warm.
I can easily build them a small house and put a blanket in it but I
would like to insulate it and maybe add heat.
Is there any electric heating pad type of thing that I can buy to use
inside this cat house.
I want it to be safe since it will be close to my house I don't want
to start a fire.
I was thinking about those electric pipe heaters that are used to
prevent freezing but not sure if they get warm enough.
Any suggestions, electric or otherwise?

They have their own fur coats. Nothing warmer.

A single 60-watt bulb is sufficient for about 50 baby chicks; I would think
a piddly heating pad would be ample for a cat.Further, I wouldn't cover the
entire floor with a heating pad just in case it's TOO hot.

You might consider a duplex cat-house (interior wall, two doors), just in
case the cats don't like sleeping together.