Crochet a Radiolarian Out of Upcycled Plastic Bottle Filament

Radiolaria have fascinated me since I first saw Ernst Haeckel’s drawings of microscopic marine organisms. Radiolaria are a form of zooplankton, the animal component of ocean plankton. If you aren't familiar with radiolaria, I highly recommend searching "Haeckel radiolaria" to see some examples. There are many different forms, and I drew the inspiration for this project from images on the main page of Radiolaria.org.

At Dinalab where I work, we’ve been experimenting with different ways to upcycle plastics, including using thin plastic as “plarn” (plastic yarn) in fiber art projects. My partner, Andrew Quitmeyer, made a lot of thin filament out of PET bottles (single use soda bottles), and I thought crocheting a radiolarian could serve as a meditation on the disastrous effects of plastic waste on ocean life.

The only skill you need is intermediate crochet. Although the actual crochet pattern is quite simple, I find it more difficult to crochet with unusual materials like this PET filament. Since the filament follows the circular shape of the bottle, it tends to kink while you crochet. This just takes a little patience and a lot of stretching out your wrists & hands!

Abbreviations used in this guide:

ch: chain stitch

sc: single crochet

sl: slip stitch

inc: single crochet increase

x 6: perform action six times

(Number): number of stitches at the end of the row

For this project, you’ll need a lot of filament made from PET bottles (plastic type 1, found in drink bottles). I would recommend cutting several bottles into filament - I used about four bottles' worth for this project, and the filament was cut very thinly. The thinner the filament, the fewer bottles you will need to make this project.

There are lots of different ways to make the plastic filament out of bottles, including this method, designed by Andrew Quitmeyer, that uses a motorized blade and a 3D printed element.

Materials needed:

• Plastic filament, 1-2 mm in width, or as thin as possible
• A large crochet hook. Gauge is not very important. Because even fine filament is fairly thick, and we will try to achieve a lacy look for our radiolarian, I used the biggest crochet hook I have, which is a size Q (16 mm).
• Scissors
• Stitch marker/safety pin
• Tapestry needle (optional)

You may also want to heat your radiolarian at the end to define its shape further. For that step, you will need the following tools:

• Heating element - I used an Einhell heat gun (available here or at the usual online retailers). You could use any type of heat gun, although make sure first that it is safe, and use adult supervision or a friend's help as required.
• A shape to help mold your radiolarian. This is dependent on the finished size of your radiolarian, but you might want to use a ceramic or metal bowl for the main part and a metal knitting needle for the pointy tip. I used a plastic funnel, but I don't recommend using plastic, because it might melt.
• Heat gloves. I used AYL grilling gloves, available here. Regular potholders aren't ideal, because you want something that covers your entire hand and protects you from high heat.

1. Using filament, crochet a magic ring with six single crochet stitches. (If needed, please consult the Magic Ring Instructable by PatronesValhalla). (6)

2. (Inc, 2 sc) x 2 (8)

3-9. Sc around (8)

10. (Inc, sc) x 4 (12)

11. (Inc, sc) x 6 (18)

12. (Inc, 2 sc) x 6 (24)

13-15. Sc around (24)

16. Sl st into first st of previous round. (Ch 3, sc into next st) around. (24 sections of chain 3 segments)

17. (Ch 3, sc into next chain section) around.

18-20. (Ch 3, sl st into next chain section) around. Note that this round uses slip stitches instead of single crochet stitches. At the end of the round, finish off and cut filament, leaving a tail if desired.

If you are not going to perform the heat treatment step, I recommend weaving in any loose filament tails with a tapestry needle at this point. Once you’ve done that, your sculpture is complete! But if you’d like to break out your heat gun, go on to the next step.

It can be helpful to have someone else assist you with this step, so that one of you can hold the radiolarian over the shaping support and the other can wield the heat gun. WEAR PROTECTIVE GLOVES WHILE USING THE HEAT GUN!!! Heat guns get very hot, and you could injure yourself without protective gear.

1. Find a supportive shape that fits your radiolarian well. Make sure that the shape will not be damaged by the heat gun. For example, you don’t want to use a plastic milk bottle, because the heat gun might melt it, and it will fuse the bottle with your sculpture. I recommend a metal or ceramic bowl or funnel, but nothing precious that you would mind damaging. For this specific shape, it can be nice to have a thin support for the tip of the radiolarian, which is why I used a funnel (although the fact that it was plastic was less than ideal).
2. Fit the radiolarian over your support. Tug it down so that it doesn’t just shrink upward when you apply the heat.
3. While one person holds the radiolarian in place (while wearing gloves), the second person starts applying heat. Point the heat gun at the plastic from about four inches away. You will see the plastic start to move and shrink. Don’t keep the heat gun in one place for too long, or that area will shrink disproportionately.
4. The person holding the radiolarian can rotate the support shape so that the heat is applied evenly across the radiolarian.
5. When you’re satisfied with the overall shape of your radiolarian, you can turn off the heat gun and remove the sculpture from the support form.
6. If desired, insert the blunt end of a metal knitting needle (or other slim shape that will not melt or catch fire) into the tip of the radiolarian.
7. While one person (wearing gloves) pulls the radiolarian down over the blunt end of the needle, the other person points the heat gun at the tip. Rotate the radiolarian so that all sides are evenly heated. While you’re pulling down, the tip should become pointier and more elongated. Make sure that the plastic doesn’t shrink so much that you can’t remove the needle.
8. When satisfied, remove the knitting needle.
9. If desired, do any further detail work with the heat gun. I went around the edges at the bottom of the radiolarian. I also made sure to heat each area where there were loose ends of filament, which forms a tight little knot that protects the work from unraveling.
10. Trim any loose ends.

Your radiolarian is complete! If you like, display it on your desk, in a box, or hang it in a place of pride with some fishing line or more upcycled plastic filament.

If you get a nice point light to shine at the radiolarian (think single LED like your phone’s flashlight LED), it makes really cool shadow patterns!