If you find the plexiglass too expensive you could use other sheet material, acrylic (
2mm Clear Acrylic Perspex Sheet Cut To Size No Waste | eBay UK ) perhaps or polycarbonate (
LEXAN(POLYCARBONATE) SHEET 3MM CLEAR 1000mm x 500mmX1NO | eBay UK ). These may be better in fact (especially the lexan as this is used, when it's thicker, in bullet proof applications) as they are more flexible and less lightly to shatter into sharp points if something goes wrong. Also it would be easier to fix a wheel to these as it's probably going to be a shade thinner.
Best of luck with your project!
