Custom Jacuzzi Access Panel - Sheet PVC

With no access panel built into the base of the jacuzzi when it was built, plumbers recently knocked a hole thru the base of the center wall to change out the fixtures. Which left a crude rectangular-sized hole. What's needed is a custom sized access panel:

7 3/4 high by 19 5/8 wide. No greater than 1/4" thick.

The jacuzzi is white, the nearby base cabinets are white, and the tile around the jacuzzi is white with subtle whispers of grey & earthtones mottling. The (2) absent sidy-by side 8 x 10's are actually 7 3/4 by 9 3/4 each at 1/4" thick

The material must be shapeable, and either attached directly to the osb -- something with some body to it since I will be using adhesive around the perimater only (the cutout left an exposed, wavy inset of the OSB, exceeding the tile by about 1/4" to 1/2" around the inner perimater)

Azek is 3/4" deep so that rules that out.

Cannot find tiles to fit at 1/4" depth, although the 20 cm by 50 cm comes close, it would need to be cut on 2 sides for a fit inside the cut-out, but these are are 3/8" deep which is too high.

Have come to the idea that a small sheet of pvc might be the best best. Since popping off any additional tiles in a continuing line runs the risk of breakage and no match can be gotten, and there are no records of what was used.

Question is does anyone know where to get such sheets of pvc at 1/4" or less and what's the best thing to cut it with? Can the edges be routered? What adhesive to use for sticking it to OSB?