The initial problem with the property of carbon atoms to create 2D structures is being capable of creating a pure sheet with a perfect aliment. This is not the only one because if the sheet has one atom thick it could be considered impractical for multiple applications. Carbon nanotubes are graphene sheets rolled in a cylinder shape. Other solutions to increase thickness are stacks or 3D structures like foam. Mixing other known materials with graphene or carbon nanotubes should also increase some desired specification as different researchers were proving the last years.
If you like to research with graphene there's a very cheap method to produce it using graphite and adhesive tape.