Can zebra strips (elastomeric connectors) be cut to size?
Zebra strips are most often custom made to size to suit the enclosure design requirements of a product designer. This is why it can be hard to find general purpose replacements. 

Using the following drawing as a reference:



Dimension H between the circuit board and the LCD glass is the most critical dimension. Proper operation normally requires the material to be slightly compressed in this dimension for the carbon material in the elastomeric sandwiches to make contact with the glass and PC board conductors. It is not really feasible to cut the material in the H dimension due to the high tolerance parallelism required of the adjacent surfaces.

It is no problem adjusting the L dimension by purchasing a longer strip and cutting it down.

The T dimension can be critical since if it is too far out of the original size it can affect how material compression works in the H dimension. It may be feasible to trim a strip with a bigger T dimension to a smaller one but I can say from experience that trying to cut silicone elastomeric materials can be very difficult using a blade in a progressive cutting action.