Only thing I have seen from HuntSmart are the Aluminum Dog Box Vents.....Haven't seen Aluminum holes in their catalog or online.
dannelboy, contact the various dog box manufacturers about having some custom made or pull up Google Images and get some ideas on how to make some for your set-up.
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CoonDawgs.com - A Site Designed for Coon Hunters
American Houndsmen - Vintage Hound Hunting
Coon Dog Cemetery - Key Underwood Coon Dog Memorial Graveyard
HuntingBassets.com - A site dedicated to hunting with Basset Hounds