What is the hole size and wire thickness on both the BM screens? (support and filter)
Are top and bottom ones the same?
Does the bottom screen slide up the centre post when the pump is running & return when it stops?
What is the flow rate of the pump set at?
What is the ratio of pump to rest breaks?
What is the total capacity to the rim of a BM 10 & BM 20 boiler? ( no grain tube inserted )?
Do I have to use 316 stainless or will 304 suffice?
Where is it best to position the thermowell in a boiler with twin elements, and does it need to extend to the center of the kettle?
Now onto the history & concept/idea/plan:-
Having seen a Grainfather in a shop last year & watching several brews on Youtube, & the same again with the Braumeister + the added benefit of sharing a brewday with Normski of this parish in December (thanks Norm

I'm not interested in the fancy timer functions of the BM, well not at the moment, so I am happy to increase PID set points manually for step mash etc., likewise the pump / rest breaks will be done manually by turning it on and off. (being modular & external I can always add a Siemens PLC or LOGO module to the control box for these options later)
I have a PID controller SSR's etc and as you've seen on my other posts have used them for test boils & fermentation temp control using a water bath & brew belt so am happy they work OK.
So I'm now onto the thermowell for the "brew kettle", assembling the controller box, & putting together the grain tube, screens & pump.
Like the BM I'm going for bottom fed/top spill over & I intend to achieve this the simplest way I can think of as below.
Basically think of a stock pot suspended/supported in the brew kettle with a hose & pipe feeding into a bottom connection
Advantages are no fancy bottom seal tube, no pump hidden under vessel, etc & totally modular & transferable to different kettles.
Spaced off the bottom of this "pan" by a "difuser arch", to spread the flow of the incoming wort, are the lower screens, coarse one/two for support & fine for filtering.
Grain is then poured in just like a BM, the top screens are inserted, again coarse and fine & held in place same way as in the BM with a spacer bar & top nut.
So far you have fancy BIAB with solid sides & pump fed base & filter plates top and bottom.
External to the boil kettle is the pump connected to the kettles normal outlet tap via a hose.
The pump, being magnetically driven, can have on it's outflow side another tap with which you can control it's flow.
From this tap a length of silicone hose goes up the outside of the kettle, down through the wort and connects onto the bottom connection on the "grain pan", or onto a length of copper pipe connected onto the bottom of the "grain pan".
As i said earlier everything is manually controlled by changing the set points on the PID & switching the pump on and off and controlling it's flow by restriction.
The grain "pan" can be disconnected & raised above the kettle and supported or lifted out entirely for external sparging, (see norms thread on this to improve efficiency)
Target price for me to build the 10L prototype, excluding the PID controlled kettle which I already, have is less than £100 + my labour /time. Hence the "VANDEEN'S BREWMISER" name

Tools I have a plenty, having built a couple of kit cars and being a confirmed tinkerer so don't have to factor them in + access to lots of things at work through friends.

So what do you all think? have I missed anything? can you simplify anything further? spot any pitfalls? make any suggestions?, but most of all can you shed some light on my technical questions from the start of the post and maybe even recommend some small volume suppliers for the pipe/pan, filter mesh, support mesh, mesh edging seal & silicone hose.
Cheers all, over to you.......