Strange crossbreed between a straightjacket and a dustbin liner. Took me less than one hour to knit and half a day to make up, including the ribbing that I added to the openings to prevent them from curling like mad.

If you knit this, calculate in advance and mark the points at the edges where the openings start and end. This will help a lot during sewing up. In my case, with a rectangle 56 cm wide and 168 cm long and a gauge of 28 stitches and 40 rows per 10 cm:

Cast on 156 stitches, put a marker between stitch 50 and 51 counted from the left edge.
Row counter 000.

• Knit to RC 176, put a marker at right edge.
• Knit to RC 216, put a marker at left edge.
• Knit to RC 259, put a marker at right edge.
• Knit to RC 335, put markers at both edges (center of piece).
• Knit to RC 411, put a marker at right edge.
• Knit to RC 454, put a marker at left edge.
• Knit to RC 494, put a marker at right edge.
• Knit to RC 670, put another marker between stitch 50 and 51, counted from the left edge, and cast off. Now fold the rectangle along the center line (between your two center markers), and the other markers will show you where to close the edges or leave them open.