Karnaugh For Blind people

Having the problem of teaching digital electronics to a blind student, we designed a haptic 4x4 Karnaugh map in a FreeCAD file to be printed in a witbox BQ 3D printer.
It consists of a simple matrix with holes and cylinders. Each cylinder stands for a '1' or 'X' bit as input in the Karnaugh map. Each square in the matrix has got a hole to insert a cylinder, in case of having a '1' or a 'X' in that box. The column and row headings (Gray code) are in Braille. The final result is the base and the 32 cylinders, 16 of '1' and 16 of 'X'. The whole set can be carried in a small plastic bag (15x15 cm).

Please, authors to be attributed are:
Honorio Martín González
Armando Muñoz Vergara
Ricardo Vergaz Benito
Departamento de Tecnología Electrónica
Universidad Carlos III de Madrid