Internal light pipe geometry can be embedded inside a larger
model that has its own independent form-factor, such as a
character (Figure 3), mobile device (Figure 4), or tangible
chess piece (Figure 5). As each light pipe can be precisely
fabricated at a given location, the process of light pipe rout-
ing to avoid intersections becomes a well defined software
problem. One current limitation of 3D printed light pipes
fabricated on the machine we have available is imperfect
light transmission with longer pipes or pipes that curve sig-
nificantly. We outline the characteristics of this light loss in
the Discussion section. We have designed around this limita-
tion to produce functional prototypes, but envision our tech-
niques can be expanded using future 3D printers that are op-
timized for optical performance.