My sister bought an older house in the eatern part of Norway. The climate there is colder than here...and our floors are always cold in December - february... so a useful and environmental X-mas present for her and her closest should be home made slippers.
The grey/purple - three treads of thin wool.
The Red - one thread tick wool, one thread thin and then feltet.
The same with the pink pair.
Cortina + a thin wool yarn.