The concrete guys only have their form board to work with.  It's 3/4" thick and if used to build a box around the vac inlet, the hole in the concrete will be too big for the vac inlet to cover.

We're already doing some stainless steel boxes to recess other stuff in the concrete walls, but the cvac is different because the inlet is small and requires vac pipe, plus high & low voltage conduit and then it all has to line up and fit once the wall is poured so seems more complex than what we're doing in other areas for TV back boxes, shades, keypads, etc.

The link Paul sent is exactly what I had in mind to fabricate, so if it's compatible with the inlets I'm using looks like there is an off-the-shelf piece available.

I think the difference is the pool guys are are just spraying and then hand trowling/finishing around things that are already set in place.  With the formed/poured walls that I'm dealing with everything has to be attached to the inside of the form board and sealed up well enough that concrete can't get in and then the concrete is poured around everything.

Laying this all out has been tricky because everything is reverse of what's shown on the plan because it's all on the back side of the form board so you have to think of everything in mirror image.  Keypads, wallboxes, outlets, thermostats, etc. are all dimensioned off seams in the concrete and concrete ties which aren't even in place yet when we set the boxes.