Several years ago, some mechanics from the Aero Vodochody factory in Prague gave us a few of what they said was an L-39 factory delivery patch. Museum pilots wore them on their flight suits until the patches were ragged. We thought the patches were so nice that we eventually had copies made.
Since the minimum order was 100 patches, we put the rest up for sale in the museum store for $5.95 (free shipping). Buying a patch supports the museum's activities.