varying crosshatch line spacing

I need to engrave a piece of acrylic to illuminate it from the sides with leds. i need to create a crosshatch fill that varies the line spacing starting from bigger line spacing on the edges to smaller spacing towards the center, something similar to a fountain fill but varying the line spacing rather than the color. please help

  • I tried blending some lines to make crosshatch -  but ended up doing something else - converting to monochrome, using cross pattern. see PDF.

  • It doesn't produce a crosshatch pattern, but a contour with some object acceleration could produce varying density of engraving.