How do I sew limbs on straight so the toy is not lopsided?

When you hold a ball and look at it, you see one side. Your brain fills in the back. Move your hand half a centimetre and the whole image shifts, so you cannot compare two positions that you saw at different moments.

A photograph freezes both sides in one image and lets you compare them directly. That is the entire trick, and it is why a phone photo catches a 4 mm asymmetry that three minutes of squinting did not.

Insert a pin where you think each limb goes, pushing it through the body at the same height on both sides. Then count the rounds: if the left arm is pinned 12 rounds below the neck, the right one must be too. Round counting is exact in a way eyeballing is not.

Photograph front and side, look at the photos, adjust both pins together until the photo looks right. Only then pick up the needle. If both pins move, the placement is being corrected; if only one moves, you are matching to an error.

Use the tail you left on the limb, not a new length of yarn. Take one stitch into the body, then one into the limb, alternating, and work a full circle around the joint so the load is spread over 12-16 stitches rather than concentrated at four.

For anything that will be pulled — arms on a toy a child carries — go round twice. On the second pass, offset each stitch by half a stitch so the two passes interlock. The joint then fails by tearing the fabric, not by coming loose.