I'm looking to make some flat sheets about 1000x1000mm is ther3 anything other than glass I can use to keep the sheet flat as I'm struggling to find a sheet of glass that size at a reasonable price. 
Can I use thick perspex and lay it on that? 

Polypropylene sheet is your friend in cases like this.  Off the shelf it usually has a high gloss finish and naturally does not stick to any resin systems.   If it is cosmetic sheet, try and get one with backing plastic as the sheet can scratch in transit and handling.


Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant

Thanks Warren I shall have a look for some 😁
What thickness would be best?