This is what i use for my bio eyes, the mesh
http://www.ebay.com/itm/SET-OF-3-COOKING-MESH-SPLATTER-SCREENS-w-HANDLES-NEW-/150544055699?pt=LH_DefaultDomain_0&hash=item230d1ffd93#ht_2655wt_689
The lens is clear acetate sheet verycheap on ebay, if people wondered, theres my secret