Simple air purifier

A simple air purifier made with computer fans and HEPA filter paper. Key being you only need to replace the HEPA paper itself when the filter gets dirty, which is times cheaper than replacing the entire filter unit. See "README-assembly instruction.docx" for bill of materials and other instructions.

Key points:
- Both double and single fan versions:
- are adaptable to HEPA paper of all width and a wide range of folded height
- requires replacing HEPA paper itself ONLY when replacing the filter
- Double fan version:
- helps with stacking up power of computer fans
- can be glued to the wall, in addition to standing on the ground
- Single fan version:
- is for those with beefy fans
- is cheaper to print and easier to install than the double fan version
- can stand on the ground only