you could try that laser dotmatrix, Just mount the lasers on to a drilled wooden frame.
Of a laser touchscreen, kind of. have the lasers setup this way(phototransistors needed)
Legend: ^=phototransistor #=laser =laser in air
##########
^
^
^
^
^
^
^
^
^
#^^^^^^^^^
so you can tell which "pixels" are blocked by finding which 2 lasers are blocked like this
Legend: ^=phototransistor #=laser =laser in air P=obstructing object S=laser path
##########
S ^
S ^
S ^
SSSSSP ^
^
^
^
^
^
#^^^^^^^^^