Based on my first-generation filter housing, this version measures 168mm x 168mm x 97mm (excluding pipe fittings) and features three dedicated slots for inserting filter modules as needed. Each module includes a pre-filter cotton pad, a HEPA filter cotton pad, and activated carbon. The low cost of consumables combined with its flexible, replaceable design makes it an ideal choice for various applications.

Primarily designed for air filtration in both photopolymerization and FDM printing processes, this unit is equipped with a 6-inch dual-speed duct fan that delivers noise levels within an acceptable range. It can create negative pressure inside sealed photopolymerization chambers, making it suitable for sanding or painting operations as well.

The filter housing body and lower pipe connections are securely fastened using M4 x 6 x 5 hot-melt nuts paired with M4 x 8 flat-head screws (the accompanying photos also show the use of M4 x 9 x 0.8 washers). Alternatively, M5 self-tapping screws can be used for installation.

The activated carbon modules are secured with M3 x 8 self-tapping screws—flat-head screws are preferred, though I didn’t countersink the holes, resulting in a slight protrusion when the screws are fully inserted. While this does create some resistance when inserting the screws, it doesn’t affect functionality.

The recessed grooves are designed to accommodate 2mm-diameter sealing strips; in practice, even without these strips, the housing still maintains excellent airtightness.

Compared to the original design, the lower interface has been enlarged to reduce airflow losses and optimize intake volume.

Two duct connection options are available: a 150mm port and a 160mm port. The “J”‑suffix model represents a lightweight variant, while the non‑“J”‑suffixed version closely mirrors the original design and includes a built‑in airflow direction indicator.

Consumables:

For the pre‑filter cotton, I opted for standard air conditioner dust filters—10 sheets for just 3 RMB (45cm x 100cm), each yielding roughly 8 pieces measuring 175mm x 175mm. It’s recommended to cut the pre‑filter cotton to size using the pre‑filter holder as a guide. Secure the edges of the pre‑filter cotton to the inner surface of the holder using double-sided adhesive. Once the cotton is properly positioned, slide it into the designated slot within the frame; if the pre‑filter cotton doesn’t fit snugly into the holder, you can apply transparent tape to help it stay in place.

For the HEPA filter cotton, I purchased material that’s 30cm wide with a 1cm pleat height. My particular purchase was 100cm long, 30cm wide, and 1cm high, costing around 7 RMB—and it can be easily cut into 12 pieces measuring 15cm x 15cm. To secure the HEPA filter cotton, simply tuck both sides of the filter into the frame’s slots.

The activated carbon module requires activated carbon and a filter mesh—either stainless steel mesh or self‑adhesive ventilation screen mesh will work. The filter mesh should measure 140mm x 140mm.

The key difference is that stainless steel mesh needs to be cut to size yourself, whereas self‑adhesive mesh only requires trimming to a length of 140mm.

I initially used stainless steel mesh, which proved quite cumbersome. My preferred method was to first tape off the areas to be cut using masking tape, then carefully trim the mesh after cutting. Finally, I’d secure the edges with additional masking tape to prevent sharp metal wires from poking out and causing injury.

The self‑adhesive mesh I purchased came in plastic form—just a quick snip with scissors and it was ready to stick right onto the frame, making the process much more convenient.

For activated carbon, I chose coconut shell activated carbon with particle sizes ranging from 2–4mm. Other types of activated carbon can also be used—as long as the particle size doesn’t exceed the mesh aperture of the filter you’re using.

You don’t need to fill the module completely with activated carbon—just enough to cover the filter layer is sufficient. Adding too much activated carbon may actually reduce airflow, so adjust the amount according to your specific needs.