Fr. Richard Leonard, S.J. And Glass Doors On Tabernacles

This piece is from Fr. Z at WDTPRS, below is an excerpt of Father John's comments.

The Precious Blood may not be reserved except in very rare cases when a tiny amount from Mass may be kept for Communion of sick people who absolutely cannot take even the smallest amount of solids or gluten, etc.Otherwise, if a tabernacle had a door made from something that was a strong as the glass that goes into military vehicles in Afghanistan, then I suppose it would be okay.  In any event, it should be veiled.  The veil, not the sanctuary lamp, is the best sign of the presence of the Blessed Sacrament.

Link (here) to read the full post. 
More on Fr. Richard Leonard, S.J. (here)