DIY Pressure Containers

THIS PROJECT USES RESIN CURING

"Liquid 3D printing resins give off fumes or vapors containing volatile organic compounds (VOCs) that can be harmful to humans if inhaled into the throat or lungs. Short-term exposure to resin fumes can result in dizziness, headaches, and throat irritation"

Use the protective equipment mentioned in the materials section, or proceed at your own risk

Materials

For this project I will converting two bottles into containers that can properly hold pressure (tested up to ~10 PSI).
one smaller bottle will not have a exit valve, while the larger soda bottle will have a barbed exit connecter.

to do this you I used:

general:

1 large soda bottle
1 small water bottle
1 air compressor (manual or automatic)
1 3d printed barbed exit cap
1 ball pump needle

sealants:
super glue (larger gaps)
UV resin (smaller air tight gaps)

safety equipment (if using UV resin):

nitrile gloves
half-face respirator

Sealing: Super Glue

To fill the larger gaps I used super glue. Using super glue helps to create a larger barrier and helps fill regions that UV resin couldn't cure, as it is not directly exposed to light.

just unscrew the cap and pour super glue onto the bottle's thread while rotating it, then quickly twist on the cap. after this wait at least 24 hours to ensure proper bonding has occurred

photo of the resin used, paintbrush and box for the resin

Sealing: UV Resin

Then use UV resin to fill the smaller gaps. the UV resin I will be using is straight from my resin 3D printer, but most UV curable resins or general airtight sealants will do.

To apply the resin I just used an old paint brush and slowly painted the edges of the thread of the cap while rotating the bottle

photo of 2 black-lights aimed while curing the large soda bottle

UV Curing

the bottles were then cured over about a total of 20 minutes (10 minutes then rotated 90 degrees)

keep going until the resin fully hardens

then I would recommend leaving the bottle in the outside in the sun for a full day to fully ensure the curing process is complete

Results

After curing I tested both bottles using the air-pump while noting the pressure. Be careful when pressuring these bottles and wait between each pump or increase in PSI to sure it doesn't decrease through a small hole.

If there is a noticeable decrease in psi over time or there is a rapid failure of the seal just repeat the process. Luckily this is all very cheap material, so don't stress.

If the seal seems good then your ready to go do fun projects with small amounts of pressure, like bottle rockets or a pressure based motor!