Just published
http://gimpscripts.com/2017/02/crazycrochet/
It's a filter to create a new image simulating a CROCHET LOOK of the INPUT LAYER.
The "crochet" image can be produced either as White over a BG, or in four different colorization.
Here some hints for its use:
Start with the option "White crochet" (default), for two reasons:
- it's the "normal" aspect of a crochet work done "once upon a time" by our beloved mothers and grand-mothers
- it's the most critical, because it does not "benefit" of the colours.
If you do not like the result, you may try to set the Texture Areas to 3 and re-test.
Or -on the opposite- you may try to set the Texture Areas to 10 and re-test.
It depends from the image.
All other options take advantage in one way or the other of the colours.
If you like to have a more traditional crochet look use "Nuanced crochet" or "Combo crochet".
They "simulate" works done using coloured threads.
The remaining two option are for those who like to have more colours.

Start with the default dimension of the output (width+height=2400); it gives good results and is fast.
Try in general to avoid to go below 2000, which may produce less nice results.
If you don't have problems of performances, you may increase the value, 3000-3600 is still quick.
If you go up to the maximum size around 9000, you may have some delay in the execution.

An enhancement version has just been published
http://gimpscripts.com/2017/02/crazycrochet/
It implements the suggestions given by Pat:
- possibility to create the crochet with a transparent BG
- possibility to create the crochet only from a selected part of the input layer
and the suggestion given by Sallyanne:
- possibility to use for the crochet an "unbleached" thread to better simulate ancient works

Hope everybody will enjoy these increased possibilities.

I love the transparency option! I applied a radial gradient to the image layer and added a black background for my experiment.

A "creative" outcome, brilliant!

Found I had to do the frame before the crochet & feathering your selection gives a 'red' mark where the selection was.

Yes, Sallyanne, it may happen because the filter uses the RED COLOUR as a mean to re-create the selection in the new image.
Hopefully not in any image...
Let me know.

My attempt.
Steps:
1- select the white puff area
2- run the Crazy crochet (out1)
3- taken the original
4- circle select around the puff
5- run the Glass Frame filter (out2)
6- copied out1 on top of out2
7- merged down

no red with these steps

note: my selection at point 1 was not very good, so you see spurious pixels, sorry