The original Dynaco ST70 was sold with a perforated sheet metal cage that covered the transformers, tubes, and the driver board. It's not unusual for folks to run these amps without the cage because it looks cool, I guess. The kits that Bob Latino sells do not include the cage, but you can get them from other Dynaco parts suppliers.
Edited to add link to replacement cage on the dynakitparts.com website: https://www.dynakitparts.com/shop/dynakit-st-70-cover/