William Bagwell wrote:

Back working on my bat house mold. Envision a large rectangular sink made of
5/16 thick cast aluminum... I'm 'milling' a shallow slot in the middle with out
a milling machine. A router with a carbide bit actually works (slowly!) as long
as I take light cuts and keep it lubed up with stick wax. Running into a
problem getting the slots all the way into the corners.

http://www.mysecondbathouse.com/smal...mold-slots.jpg

Have already booked some run time at my local rotational molder next month and
would like to connect the slots before then. Only real machine shop I can
possibly afford (semi retired relative) is not open on my normal days off and
my day job is oddly wide a** open. Running out of time and ideas so I'm asking
here.
--
William

I suspect that in the olden days such a slot would be cut with a chisel
(not a wood chisel), also suspect that would still work today...