Not sure if it's been reported already, but photons can (occasionally) pass right through BMTL. Try it.
Make a circle of normal metal, then a circle of BMTL, and put some photons in the center of each.
Metal, they'll bounce around like normal. BMTL, some will bounce and some will just fly right through.

EDIT: This is probably related: https://powdertoy.co.uk/Browse/View.html?ID=426476

64.3 minor bug fix?

@cracker64
hi i saw this and i was wondering if there is anyway to make it so the new element conv could change colour with something like this?

@mniip
could you elebarate on that?

the water equalization thingy... yes its a good feature but the equalization doesnt know when to do it right.
the _ are walls the w is water
____ _ _w _w _
_ _ w _ _w _w _
_w _ w _ _w _w_
_www _ _www_
see here the water shouldnt the water here should go up and it does
go up because of pressure,
yet in tpt, it does

all in all, it is a great addition to tpt, but it could use some tweaking, and to critics, dont tell me to code it myself