Pyro's.
I'm contemplating using ceramic glass to form the roof of a batch box as a means of porting heated secondary air to the riser throat.
The plan is to have one sheet of ceramic glass as the ceiling of the batch box and use say, 1 inch of ceramic fiber board around the perimeter of the glass panel and then top it off with a sheet of ceramic fiber (or other suitable material) in order to create an air gap with a path through the system from the door to the riser throat.
If used in a Double Shoebox type setup, two panes of ceramic glass could be used so as to capture heat from the secondary as well as the primary firebox.
The working idea here is to capture as much of the early startup heat as possible and get the air in the airgap warming up as soon as possible to help fuel the secondary burn. You might wonder why I would want to have the secondary air entering the system so much farther up from the port, (I can see Peter scowling at me now) but the system I have in mind will be using a space resembling that of a cyclone separator in order to capture the hottest gases in a circular path that encourages turbulence through the use of (trip wires) on the ceiling of the chamber ring. As the gasses expand and cool, they will spiral downward to the bottom of the cone, dropping their load of
ash and particulates in the collection chamber at the bottom. Once gases have reached the bottom of this cyclonic secondary chamber, they will spiral back up into the inside tube and make their way to the back end of the system,
oven, bench, cooktop, radiant bell/drum, or with the use of dampers, maybe more than one.
I propose building the firebox and what I will call the Combustion Cyclone out of a
aerated (foamed) mix of castable refractory cement, bulk ceramic fiber, and pearlite. I expect to use some ceramic paper product with which to form the inside tube for the Combustion Cyclone. Sodium Silicate will be used on the ceramic paper as it is rolled into form on a 8 inch diameter tube. (8 inches as this is the size of the system I am targeting.)

I have followed the adventures of a certain
Honey Do Carpenter on Youtube who has made a name for himself with his experiments in foamed Portland cement. Seeing his success in that endeavor gives me confidence that same can be achieved to some degree with the 60% alumina castable refractory I have available. This
video shows how his aerated cement can be poured into panels.
https://www.youtube.com/watch?v=MXs-tqfCSX0
Such an aerated mixture could also be easily poured into molds to create more complex forms.
This is where you guys get to pick this apart and ask me questions about things I have overlooked.
It's high time I started this build, so I think I will start with the bench, that will give me time to get these other details sorted out. I'll probably keep documenting this build here so if any of this intrigues you, then please follow along.