Motoworks do complete units, but I doubt if they only do replacement perspex parts.
One shown below imo is best, with fold down protector so glass can be cleaned.
Quick link:- motorworks
Many companies specialize in cutting Perspex (acrylic) sheets to shape, including online retailers that offer custom cutting services. You can find services that allow you to specify dimensions and shapes for your Perspex sheets, ensuring a precise fit for your project.