Here's my contribution to three weeks for Dreamwidth.
I was inspired by
azurelunatic's Dreamsheep. (And I've volunteered the
crochet community to help write up a pattern, and test-crochet it). I realised the Dreamwidth swirl spirals the same way as my crochet (I'm left-handed):

This is my first written-out pattern, so be gentle. I deliberately went tight (smaller hook size) to get a solid effect. The two larger (shinier) swirls are made from 8ply tencel/wool (yarn thickness also known as DK, the yarn size that recommends 4mm knitting needles) and the smallest is made from 3ply crochet cotton (I guess this would be fingering thickness?). The point is, I don't think it matters much what yarn you make this from, except in terms of finished size. That's a cm ruler at the bottom, there:

You will need:
Directions:
With M, make 9sc on a magic ring, before pulling closed. Into the first st, slip stitch + sc. Into the next 5 st on the ring, two sc. Into the next, sc + hdc. Into the next three (the last one is the slip stitch), 2 hdc. Into next st: hdc + dc. Into next st: 2 dc.
Pull the free loop out large so nothing will happen while you work with the new colour.
With C, pull a loop through the next st, chain through it, and then work sc in the same st. [ Into next two st: sc. Into next st: 2sc. ] Repeat [] five more times.
You should be almost at the end - just a few M dc left below. Pull the C free loop out large, and transfer the hook back to the M free loop, pulling down to size to continue in M.
{In first C st: 2hdc. Into next two: hdc.} Repeat {} three more times (four total). Call this pattern {2, 1, 1} Then into next st: 2hdc. And next three st: hdc, i.e. a {2, 1, 1, 1} pattern, do this three times.
You should be almost at the end of C. Switch hook back to C, as before.
Into next three M st: sc. Into next st: 2sc. NB: for me, this means the 2sc do NOT go into the gap between the M dc and M hdc on top of first C. If you need to jiggle where your 2sc go to avoid that space, do so. Into next three st: sc. Into next st: 2sc. Into next two st: sc. Into next st: sc + hdc. Now continue in the {2, 1, 1, 1} hdc pattern until you're nearly out of M st. Into the next stitch you'd do 2hdc, do hdc + sc instead, and sc in the next st. Cut C and pull through.
Working with M again: continue in {2, 1, 1, 1} pattern. Change to a {2, 1, 1, 1, 1} pattern about where the C switched to hdc. If necessary, adjust where the 2s go a bit so they don't happen on top of each other. If the 2s are on top of each other the shape will look more angular, less swirly. When you get to the end of C, avoid 2s in the last few stitches. Instead, do 2 dc in the first M stitch after you run out of C stitches, a "step down". Into the next two st: dc. Into the next st: dc + hdc.
Now continue in {2, 1, 1, 1, 1} hdc pattern, either for just one repeat (if you want it to be over quickly, per the blue swirl) or continuing around one more time (per the red/white swirls), moving to a {2, 1, 1, 1, 1, 1} pattern again about where the C thickens to hdc. The extra time around is particularly useful for hiding any bumpiness around the step-down at the end of C, and
Finish with hdc + sc in a st, sc in each of the next two st, slip stitch in the next st. Cut, pull through, finish ends. Sew to bag, or anything else that needs Dreamwidth swirls.
It wouldn't surprise me at all if different people find they need to space the 2s differently, and increase spacing between them differently than I did. That's fine (none of my three are identical). Just try to avoid 2s in the step-up or step-down around the start and finish of C, and avoid 2s on top of each other.
Since I've only been doing these today, and I mainly wanted to establish proof-of-concept, I doubt this is even the optimal pattern for me. But I'm happy with them in the proof-of-concept sense and did want to get something out for 3W4DW.
I'm toying with the idea of whether it's possible to modify this approach into a full-blown swirly D, but I'll leave that for now. And if you really like Dreamwidth, I'm sure these swirls could be the base units for a rug/blanket/afghan, but then you'd probably want to crochet more loosely/normally, and just accept the more open texture.
* If you're right-handed, I can think of these possibilities: you learn to crochet left-handed; you teach a left-handed friend to crochet; you make it and hope no-one cares it's a mirror image; you make it and use the back; you make it and take a photo you flip, and only use the photo; you embrace the experience of what it's like to be the wrong handedness, for once. For reference, here's a photo of the back of mine:

The white really blows out in photos, but I do think the front is more attractive in person.
I was inspired by

This is my first written-out pattern, so be gentle. I deliberately went tight (smaller hook size) to get a solid effect. The two larger (shinier) swirls are made from 8ply tencel/wool (yarn thickness also known as DK, the yarn size that recommends 4mm knitting needles) and the smallest is made from 3ply crochet cotton (I guess this would be fingering thickness?). The point is, I don't think it matters much what yarn you make this from, except in terms of finished size. That's a cm ruler at the bottom, there:

- small amount of main colour M (i.e. white) - I used 7m for the smaller, about 12m for the larger - depends on whether you go around an extra time or not, obviously
- small amount of contrast colour C (i.e. red) - I used 2.5m for the smaller, 4m for the larger
- hook as recommended for the yarn, or smaller
- left-handed crocheter *
With M, make 9sc on a magic ring, before pulling closed. Into the first st, slip stitch + sc. Into the next 5 st on the ring, two sc. Into the next, sc + hdc. Into the next three (the last one is the slip stitch), 2 hdc. Into next st: hdc + dc. Into next st: 2 dc.
Pull the free loop out large so nothing will happen while you work with the new colour.
With C, pull a loop through the next st, chain through it, and then work sc in the same st. [ Into next two st: sc. Into next st: 2sc. ] Repeat [] five more times.
You should be almost at the end - just a few M dc left below. Pull the C free loop out large, and transfer the hook back to the M free loop, pulling down to size to continue in M.
{In first C st: 2hdc. Into next two: hdc.} Repeat {} three more times (four total). Call this pattern {2, 1, 1} Then into next st: 2hdc. And next three st: hdc, i.e. a {2, 1, 1, 1} pattern, do this three times.
You should be almost at the end of C. Switch hook back to C, as before.
Into next three M st: sc. Into next st: 2sc. NB: for me, this means the 2sc do NOT go into the gap between the M dc and M hdc on top of first C. If you need to jiggle where your 2sc go to avoid that space, do so. Into next three st: sc. Into next st: 2sc. Into next two st: sc. Into next st: sc + hdc. Now continue in the {2, 1, 1, 1} hdc pattern until you're nearly out of M st. Into the next stitch you'd do 2hdc, do hdc + sc instead, and sc in the next st. Cut C and pull through.
Working with M again: continue in {2, 1, 1, 1} pattern. Change to a {2, 1, 1, 1, 1} pattern about where the C switched to hdc. If necessary, adjust where the 2s go a bit so they don't happen on top of each other. If the 2s are on top of each other the shape will look more angular, less swirly. When you get to the end of C, avoid 2s in the last few stitches. Instead, do 2 dc in the first M stitch after you run out of C stitches, a "step down". Into the next two st: dc. Into the next st: dc + hdc.
Now continue in {2, 1, 1, 1, 1} hdc pattern, either for just one repeat (if you want it to be over quickly, per the blue swirl) or continuing around one more time (per the red/white swirls), moving to a {2, 1, 1, 1, 1, 1} pattern again about where the C thickens to hdc. The extra time around is particularly useful for hiding any bumpiness around the step-down at the end of C, and
Finish with hdc + sc in a st, sc in each of the next two st, slip stitch in the next st. Cut, pull through, finish ends. Sew to bag, or anything else that needs Dreamwidth swirls.
It wouldn't surprise me at all if different people find they need to space the 2s differently, and increase spacing between them differently than I did. That's fine (none of my three are identical). Just try to avoid 2s in the step-up or step-down around the start and finish of C, and avoid 2s on top of each other.
Since I've only been doing these today, and I mainly wanted to establish proof-of-concept, I doubt this is even the optimal pattern for me. But I'm happy with them in the proof-of-concept sense and did want to get something out for 3W4DW.
I'm toying with the idea of whether it's possible to modify this approach into a full-blown swirly D, but I'll leave that for now. And if you really like Dreamwidth, I'm sure these swirls could be the base units for a rug/blanket/afghan, but then you'd probably want to crochet more loosely/normally, and just accept the more open texture.
* If you're right-handed, I can think of these possibilities: you learn to crochet left-handed; you teach a left-handed friend to crochet; you make it and hope no-one cares it's a mirror image; you make it and use the back; you make it and take a photo you flip, and only use the photo; you embrace the experience of what it's like to be the wrong handedness, for once. For reference, here's a photo of the back of mine:

The white really blows out in photos, but I do think the front is more attractive in person.
no subject
no subject
no subject
It's the desired pattern that's going to be the bad kind of fun for anyone who does not actually have a reasonable facsimile of a 3D modeling program in their head.
no subject
I think you're right that it doesn't matter so much how the hemispheres are constructed, but other people often like explicit step-by-step until they realise it doesn't matter much. For example, I'm going by your photo to try to figure out roughly how many rounds/spirals are in your hemispheres.
no subject