Crochet a rectangle with any pattern you like as long as long you want your sleeves to be. After you finish knitting, try it on and pin it from both sides where you are going to make the armholes. Then take it off and complete the sleeves up to the pins. Then make a design. Choose an expanding pattern, for example, some shells like this and knit the sleeves first. Then knit all the rest around and it’s done.
To extend the back you’ll have to do more knitting, so there will be a collar instead of a stand. You may not extend the pattern too much if don’t want to. Choose viscose and cotton so the shape will retain. Viscose won’t let it stretch out.
The primary pattern is double crochets, 2 chain stitches, 3 double crochets, 2 chain stitches etc.
The edge knitting
You can also knit the bolero like this:
Bolero master class to make it clearer.
1. Knit the canvas upwards (from the beginning of one sleeve to the end of the other sleeve). (use crotchet) Cast on 80 loops.
Canvas should be 100 cm long (for a not too long sleeve).
2. Fold it in halves and make up the sleeves (a hole in the middle).
3. Here’s what you get.
Then knit the cuffs and the hole in the middle. Here’s the result.