55-gallon drum lids are probably relatively inexpensive for their thickness.
$30-$40, 24" diameter, 9lbs, 18ga steel
http://www.newpig.com/pig/US/unlined-re ... by_productBuy a 55-gallon steel drum, build the LISA so it suspends from the lid, put the electronics on top of the lid and then you can lower it all into the bucket for a heated enclosure.

On a side note, I've always wanted to design a printer that attached to opposite ends of the rim of a drum/bucket, with wheels that drove a single axis in circles while the head moves from one end of the axis to the other and drops with a screw to print off the bottom of the container.
