Vellum is a great medium for paper crafting as it's semi opaque finish adds a partial layer to projects with colours and designs underneath still showing through slightly. Vellum can be die cut, stamped, dry and heat embossed and coloured with marker pens making it a very versatile product. 

Acetate is great for adding windows and clear sections to cards, as with vellum it can be coloured to create a stained glass effect, die cut and stamped on, this particular acetate is also heat resistant so can be safely heat embossed without danger of it melting. 

Spellbinders Craft foil is actually very thin sheets of metal foil rather than a foiled card, as such it can be bent and shaped and will hold it's shape and can also be dry embossed with spectacular results.