They are some kinds of "rhombic crosses", of the same category as the well-known Rhombic Star, or Snowflake from Pentangle.
The first one consists in 24 identical pieces that form a cubic box with 4 pieces per side :
It works thanks to a kind of general coordinated move that is awfully tricky to perform in the assembling direction.
The second one looks the same, but is has 28 pieces, including 2 solid keys, and works more or less like the Snowflake (no coordination required, although you can be tempted to use some if you can't find the only assembling order where no piece hinders any other).
It seems that this design can be extended at will. Here are two giant versions, in the background, with respectively 94 (4 solid keys) and 102 pieces (6 solid keys) :
These two ones may be Maurice Vigouroux's own creation.