Jeg startede med at fjerne lynlåsen.
I removed the zipper.

Jeg ville jo have at lynlåsen skulle kunne give sig i bredden, når jeg tog støvlerne på. Det ville have krævet elastik, der var lige så bred, som lynlås-slidsen var høj. I stedet tog jeg almindelig bred elastik bredde. Jeg klippede det adskillige 3 cm brede strimler, som jeg syede sammen på den modsatte led, således.
I wanted the elastic to be stretchy width-wise. That would require an elastic with the width of the height of the zipper slit. In stead I took regular wide elastic, and cut it into several strips 3 cm wide (slightly more than 1″). And then I stitched them together on top of each other.

Nu havde jeg en lang strimmel elastik, der var elastisk i bredden.
Now I had a long strip of elastich, that stretched widthwise.

Og så syede jeg ganske simpelt elastikken i slidsen ved at bruge de eksisterende huller og stærk tråd (skindtråd ville være velegnet, jeg brugte stoppegarn, for det havde jeg lige ved hånden i den rette farve). Det var ikke særlig svært, men det tog en del tid.
To pæne sømme på hver side af slidsen med små små sting, fange foret på bagsiden og sørge for at alt var godt fastgjort.
Then I simply placed the elastic in the slit and stitched it to the boot using the existing holes. It wasn’t difficult, but it took quite a long time to finish them.
Two seams on each side of the slit made with tiny tiny stitches, catch the lining in the stitching and making sure everything was sturdy.

Endelig færdig:
Finally finished:

Et småmystisk billede, viser hvordan elastikken giver sig, når jeg trækker foden op af støvlen. Den sære klump bagpå er min hæl, der er på vej op. Det virker!
I curious picture to show hiw the elastic gives, when I pull my foot out of the boot. I ood lump in the back is my heel.

Hurra, det virkede, jeg kan bruge mine støvler igen. Lige i tide til vinteren…slud, sne, hagl, tø og regn, kom bare an.
I feel like dancing in the snow!…..well the sleet.

Jeg ventede med skosværten til efter billederne, da det jo ikke handlede det jo ikke om at give støvlerne en skøndejlig makeover, men om at gøre dem brugbare igen.
I didn’t pretty them up with shoe polish until after I had taken the photos, as this was a refashion, not a makeover.

Edit: Flere har spurgt om de nu ikke er vandtætte, og om det ikke trækker ind ved elastikken:
Faktisk tror jeg at
støvlerne er mere vandtætte, end de var før. Lynlåsen var i forvejen ikke vandtæt. Det kan jeg huske stod på mærkaten.

Edit: Several people have asked if the boots are not waterproof anymore now. I think the boots are more waterproof than before. The zipper was not waterproof, it said so on the tag.
The elastic is a heavy one, and no cold or moisture has come through the elastic. I wore the boots all of last week in rain and snow and sleet and hail,
and they are quite waterproof and coldproof.
And what you can’t see is that the lining is pulled close towards the elastic at the back, and the the lining has a waterproof membrane.
They probably wouldn’t hold up,
if I wade in ancle-deep puddles, but I wouldn’t expect that of a pair
of winter boots anyway (and then the water would come through the front flap anyway).
If I wanted to completely waterproof the boots, I could have put in a piece of rain clothes’ iron on tape, but I didn’t think it was nessassary. If I change my mind, I can easily add it.