In many projects you need to cut out symmetrical shapes, or mirror image shapes.
It’s easiest to cut these by using folded fabric.

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Cut symmetrical shape

You need a pattern piece for half the shape, which you place on the fold.
For example, half a heart.

heart patt

The general convention of pattern markings is to use a double arrow to point to an edge that is placed on a fold.

Place that edge of the pattern exactly on the fold. If it’s away from the fold, the cut fabric will be wider or narrower than intended.

Cut out around the edges of the shape that aren’t on the fold, but
don’t cut along the fold edge.
The result is a whole symmetrical piece.

heart open

The same applies to cutting out a symmetrical part of a garment, such as a back or a collar.

back pattern

back open

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Cut mirror images of same shape

Suppose you want front and back of the same shape, such as a Christmas stocking. If you cut from folded fabric, you can cut both front and back at the same time.

Place the pattern piece on folded fabric, but not on the folded edge.
Cut out, and you get 2 mirror image shapes.

stocking fold

One piece of folded fabric automatically has Right Sides Together (RST) or Wrong Sides Together (WST), and usually it doesn’t matter which.
Though it often saves a step if you cut out RST – then the two pieces are already aligned. So with a shape like a stocking, you can sew the two shapes together directly without having to move the fabrics around.

stock tog stock 1/2 open

stock open

On the top layer, the pattern shape is cut out from the back/ wrong side of the fabric. On the lower layer, the pattern shape is cut from the front/ right side of the fabric.

The same cutting method applies to cutting out parts of a garment which are mirror images, such as two fronts or two sleeves.

front patt

front open

You can get the same result by placing two unfolded pieces of fabric right sides together (or WST).

stock patt on 2 fabrics

stock 2 fabrics open

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Take care with cutting out plain/solid fabric, as the left and right pieces will look the same.
Best to mark the right or wrong side of the fabric before separating the pieces.
I prefer to mark on the wrong side of the fabric, as there’s always a possibility that a mark will not disappear completely.

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When you have to cut out mirror image pieces from a single layer of fabric, place the pattern piece once face up, and a second time face down. (A pattern cutting layout plan will show the two pieces with different symbols.) This has the same effect as using folded fabric, but is double the work !
You may want to do this in special situations, such as fussy cutting patterned fabric to get the pattern on the fabric in the best place.

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