Grid for Pocket tactics v4

Trying to make a 7-piece to easier put tiles on for the awesome Pocket Tactics: http://www.thingiverse.com/thing:1820557

v3 seems ok =)

v0: with 20mm hex-inside walls and 2mm high
v1: with 19mm hex-inside walls and 3mm high
v2: with 19,2mm hex-inside walls and 3mm high (v1 was a little snug)
v3: 19,2 fit nicely! Now with a full hex grid. Comments appreciated.
v4: alternate version with slots