Cute Squirty Octopus

I have been experimenting with modifying McGuybeer's excellent Cute Mini Octopus since last year, mostly adding screw threads to attach them to bottles. After a lot of testing, here is a straightforward modification which upgrades this critter to a functional water squirter, with the addition of a common beverage bottle. (A thin-walled, squeezable bottle for best results.)

Additional thanks to steffanders for the PCO28 bottle thread models of which I used the “cap without vents” for a nice reliable internal thread form. I started using this last year before making my own threads in other models, and didn't need to change it here.

Design Notes

The model simply cuts out a bottle cap thread and a funnel-shaped water channel through the mouth. Being made in Tinkercad, it's not too refined in its finish and the water flow could probably do with more optimisation, but it works.

Unlike the inside top of a normal bottle cap, the lip seal is not flat as it's very challenging to print multiple overhanging perimeters together on a single layer without sagging. I've tried a flat lip with supports, but the finish turns out rough so it's a worse seal than the inclined alternative I have used. This isn't perfect but it seals well for the purposes of this model.

The little cylinder at the back is to help with centering the model; it doesn't clash with the octopus model so does not affect the print.

Models Included

Primary model is "Squirty Octopus_thread-spout.stl" which is used to cut out the thread and mouth spout. There's also a cap thread with no spout, if you just want an octopus bottle cap. (Requires octopus to be same scale as the spout version.)

There are pre-modified octopus .stl files for slicing, as well as some prepared .gcode examples and associated .3mf projects of two variations - one heaver with more perimeters and another lighter, faster and only using just under 10 metres of filament if you have a sample spool.

Self-Assembly and Printing Notes

• Import “Octopus_v6.stl” or “Octopus_sup_v6.stl” from Cute Mini Octopus and scale uniformly to 122%.
• Import "Squirty Octopus_thread-spout.stl" and merge with the octopus, making sure they are centered with each other and touching the build plate.
• Convert the spout to a negative volume.

You will need to set your own support under the mouth if using “Octopus_v6.stl”.

PLA and PETG both work well, but you might get better results with PETG if you scale the thread/spout to 101% in the X and Y axes as it gives a slightly looser fit.

Quality of the bottle lip seal on the print will depend on your print result - I think it comes down to how flat the seam is printed at the lip seal, but having thin model walls / too few perimeters may also be a leakage factor.