Loooper could - he's not building yet because of his wrists. Might still be a little while. I have the exact thing minus the blend pot. He could do it no troubles though. I also got a "ON" button to easily bypass/turn on loops and a Tuner Mute with mine.
so you want A&B to run parallel to each other? that's what the picture seems to imply. Big issue there: you'll probably want some buffer before the blend knob to account for the extra impedance introduced by the parallel split.
If you're thinking A serial into B, then you get a whole bunch of issues with regards to turning you're "blend" and maintaining the same volume. I'm having a hard time imagining this setup without your dry signal running parallel to the two loops.
In other words, what are you looking to do?
Unfortunately I think Loooper will not make a return. He stopped building years back. You could try Loop-Master or someone similar, don't know what they would say
lastly, it would be pretty expensive, but something like the Sound Sculpture Switchblade would do this and a host of other things, but we're talking a whole different level of overall complexity. Here for their explanation about serial vs parallel loops and such.