This is a case for the 2A Micro USB boost converters found all over AliExpress. The chip used is an MT3608 but the chip is marked as "B6286 (K)"

I use mine to test my 12v projects from a 5v USB powerbank instead of firing up the bench supply. As they can go up to 28v I thought I'd make a case for it.

There's a hole on the side for screwdriver access to the potentiometer. You could perhaps make the case 1-2mm narrower and have the pot sticking out the side.

Round corners for nice printing and press-on lid that requires no glue.

I've printed using FlashPrint in PLA with 0.30mm/15% infill and also 0.18mm/100% infill for more rigidity and it looks smoother.

Don't bother with supports, the holes are so small its actually better without supports which can make the edges look messy when removed.