This model fits most tablet sizes, but can be made smaller or larger for your needs on TinkerCAD.

It's 19.5 inches length, 17 inches height, and 1 inch think. Device cutout is 11.3 inches length, 8.7 inches height, and .5 inch thick.

The board is fully customizable. You can change where the charging port is, how big the tablet cut out is, and the stylus location.

Editable File: https://www.tinkercad.com/things/8c7QPNywF4L-sketchboard-pro-alternative-tablet-drawing-stand