This uses approx 12g yarn.

Start with 4mm needle with MC.
CO 28 st with long tail cast on.
R1-3: * k2 p2 rep from * to end.
R4: * k1 m1r k1 pfb p1 rep from * to end. 42 st.R
R5-6: * k3 p3 rep from * to end.
R7: * k2 m1r k1 p3 rep from * 6 times, k3 p3. 48 st.
R8-9: * k2MC k2CC rep from * to end.
R10-11: * k2CC k2MC rep from * to end.
Repeat R8-11 once more.

Switch to CC and 3.5mm needle.
R16: k all st.
R17: * k1 p1 rep from * to end.
R18: * k1 sl st purlwise wyif rep from * to end
R19: * sl st purlwise wyib p2 rep from * to end
Transfer all purl stitches to a second circular needle and kitchener stitch the inside to the outside.