First of all find your hepa filter, then build a box around. Open a hole on top to accomodate a air blower which can
be operated through a variable power device to set the
blower speed at will.
If you can get hold of a book from Paul Stamets "Growing
gourmet mushrooms" (i don't remember the exact title)
you'll find there all you need to build a home made laminar flow cabinet.
Good Luck
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 Jean Pierre Adrien
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