Oh I am sorry so your question is ... you want plans to build a brick, rocket, cooking stove that might fit on top of a low table and is a J tube better than a L tube?
Can I first explain that a properly working
rocket stove made from brick is going to be around four feet tall and weigh far more than an average table can take.
I think you might be looking at something that most people on this forum would not consider a proper
rocket stove!
Perhaps a metal construction like the many that can be found on YouTube might suit your needs better.
Unfortunately metal is not a good option for a rocket stove that is working at its best because of the extreme temperatures that are reached but it might suit your needs if you don’t need hight temperatures or total fuel combustion?
What this forum specialises in is based around a specific set of dimensions and criteria that allows total combustion of the fuel
wood.
This requires a heavily insulated fire box and heat riser, inside the heat riser the temp can reach 2000f and heat a cooking plate to over 1000f
Both J tubes or L tubes can work but in my mind a J tube is easier to operate.
I do not know of any plans to suit your proposed idea.