The back board on these I Love Art 3D Box Frames is made of MDF. Objects can be fixed to it (perhaps mounted on coloured paper) so they do not touch the glass, which is ideal for pastels. Or with the help of spacers they can be mounted so they 'float' freely behind the glass. The frames have a profile of 40mm deep by 20mm wide. There is a non-removeable spacer bar of 28mm.
Price per frame.