BSC Bottle Holder
A biosafety cabinet has less usable deck than it looks like it has. Bottles of media, PBS and trypsin drift to the back where you can’t reach them past your own hands, or sit in the middle where they are in the way of everything. This is a printed rack that stands them up in a fixed order along one side, off the part of the deck you actually work on, and does it without blocking the grilles.
The grilles are what make the cabinet a cabinet. A Class II BSC protects you and your culture by pulling air down through the front and rear grilles — that downflow is the containment. A rack sitting on a grille, overhanging one, or spanning the deck as a solid block changes where that air goes. Keep the footprint small, keep it well behind the front grille, and keep it clear of the rear one. If your cabinet is shared or certified annually, ask whoever certifies it before you make anything in there a permanent fixture.
Parts
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Print it in PETG. That is the whole material decision and it is worth getting right: this thing gets wiped with alcohol every time the cabinet is used, and in a lot of labs it sits under a germicidal UV lamp all night. PLA goes chalky and brittle under UV-C and crazes with repeated alcohol contact. PETG shrugs off both for years.
- eSUN PETG filament, 1.75 mm, solid white — one 1 kg spool is plenty. White on purpose: a spill or a dried ring of media shows up on white and hides on black.
- SUNLU PLA+ 1.75 mm, black, 4 × 1 kg — for the test print only. Print one bottle well in PLA+ to check the fit, then print the real thing in PETG.
- Overture TPU, 1.75 mm, white — for printed feet. A rack on a stainless deck skates when you pull a bottle out one-handed, and TPU feet stop it with nothing adhesive in the cabinet.
- Self-adhesive clear rubber bumpers, 200 pcs — the no-second-filament version of the same fix. Four under the corners. Expect to replace them: alcohol creeps under the adhesive eventually, which is why the TPU feet are the better answer if you can print them.
- Solimo 99% isopropyl alcohol, 16 oz × 12 — dilute it to 70% before you wipe anything with it, roughly seven parts alcohol to three parts water. Neat 99% evaporates off the plastic before it has done anything useful.
- Neiko digital caliper, 0–8 in — you need your own bottle diameters before you print. See below.
- AFA deburring tool — an elephant’s-foot lip or a stringy bore is a place liquid sits. Ten seconds per opening.
Optional, and only if you split the model to fit your bed:
- ruthex M3 brass heat-set inserts, 100 pcs
- VIGRUE M2/M3/M4 stainless screws and nuts, 1080 pcs — stainless, not the black alloy kits. Black-oxide and black-zinc screws bloom rust after a few months of daily alcohol, and rust streaks down a white rack look exactly as bad as they sound.
If you label the positions, use a laminated-tape labeller — a Brother P-touch with TZe laminated tape. Thermal paper labels last about a week of alcohol wipes before they lift at a corner and go grey.
Print settings
| Setting | Value |
|---|---|
| Layer height | 0.2 mm |
| Perimeters | 4 |
| Infill | 30% |
| Supports | None |
| Material | PETG |
| Nozzle and bed | Whatever your slicer’s PETG profile uses |
Four perimeters rather than the usual two, because the rack gets lifted out of the cabinet fully loaded and a 1 L bottle of media is a kilo on its own.
Orient it so the bottle wells open upward and print with no supports. Support material inside a well leaves a scarred, stepped surface, and the inside of a well is precisely where a drip ends up — that surface wants to be the smoothest the printer can give you, not the roughest.
If it is wider than your bed, split it between wells rather than through one, melt M3 inserts into one half and bolt the two together with stainless. A joint across a well is a crevice with liquid in it.
Sizing it to your bottles
Lab bottles are not a standard. A 500 mL bottle and a 1 L bottle do not share a diameter, and two brands of 500 mL bottle often don’t either. Measure the widest point of the body of the bottles you actually use, with calipers, before you slice anything.
Then add about a millimetre to the diameter of the well. A well cut to the exact measured size will accept the bottle on the bench and refuse it in the cabinet, because in the cabinet you are gloved, working at arm’s length, and not looking straight down at it.
Measure the cabinet too. The height that matters is not the internal height — it is the clear height at the sash’s working position, because that is the gap the rack has to come back out through at the end of the day. A rack you have to raise the sash to remove is a rack that stays in there dirty.
Before it goes in the cabinet
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Deburr every opening. Run the deburring tool around the top edge of each well, and knock the elephant’s foot off the base.
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Wash it in warm soapy water and rinse it properly. A fresh print carries release agent, finger oil and loose plastic dust, and none of that belongs on a cabinet deck.
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Dry it completely, then fit the feet — TPU pressed in, or four bumpers under the corners on a surface you have just wiped with alcohol so the adhesive gets a clean start.
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Wipe it down with 70% on the way in, the same as everything else that enters the cabinet, and load it before you start work rather than during.
What it is not
Do not autoclave it. PETG softens around 80 °C. An autoclave cycle runs at 121 °C. It will come out as a puddle with your bottles’ shapes in it.
It is also not sterile and cannot be made sterile. An FDM part is porous by construction — the layer lines are a surface no wipe reaches into. Treat it as furniture: it holds closed bottles, it never touches anything sterile, it does not go near an open bottle mouth, and it comes out and gets cleaned on the same schedule as the cabinet.
If your cabinet runs its UV lamp overnight, take the rack out. PETG survives UV-C far better than PLA does, but “better” is not “indefinitely”, and a rack that lives in the beam will chalk and go brittle at the thin sections eventually.
Files & downloads
The model isn’t posted yet — that is the missing piece here, and it is why this page is still flagged as unfinished. Everything above holds for any bottle rack going into a cabinet in the meantime.
The source files for this project aren't in the repo yet — there's nothing to download
beyond the notes. They land in projects/bsc-bottle-holder/ when they do, and this
section fills itself in.