Got my first Billet Box in 2019 and never looked back- tinkerer's heaven. Perfect for my style of rdl vaping.
Billet Boxes were the first All-In-One device as far as I know, circa 2012.
The term "boro" that we all use now to describe a format of AIO that fits a certain sized tank, comes from the original enclosure that houses Billet Box bridges (attys).
The material that the sliding door is made of is
borosilicate glass. This photo shows the sliding glass door half open.
View attachment 992105
I still like this type of tank but in recent years there have been plenty of variations, upgrades, improvements made to the design that are less fiddly and easier to fill.
I don't use my billets much these days because there are many smaller single 18650 boro-format aios on the market that have improved airflow.
One major problem with the Billet Box design is the placement of the board in relation to the tank. Sits directly below it. Many a billet user (me included) has had a leaky bridge that dumped juice all over the board and fried the electronics.