I'd like to get some opinions from the members concerning the use of non-Lego pieces in a custom MOC. While I strive to keep traditional non-Lego pieces out of my bin (Mega-Bloks for example), my question is geared more towards the use plastic pieces to accentuate structures.
Since my MOC is Blacktron I themed, it isn't in my budget to fork over $20 dollars or more for the rare trans-yellow quarter panels offered on Bricklink. Nor did Lego create a 1x6x5 window frame in black (only blue, brown, and grey) My idea was to use transparent yellow pieces of acrylic (Plexiglass) for use as a large panoramic window for one of my buildings.
Is this completely frowned upon? Or is it acceptable to a degree considering that the piece needed wasn't created by Lego?