This fun project doesn't require a lot of fabric so you can recycle old t-shirts and tops instead of buying new fabric. The bloomers in the picture are cut in one of my sister's old tops.
Use only stretch fabric for this project.
PATTERN AND CUTTING
For a 3 year old, print the pattern so that the reference line on the right measures 10cm.
Scale it up or down for an older or younger child (you won't need to scale it a lot).
A: Cut 1 in main fabric
B: Cut 2 in main fabric
C: Cut 1 in main fabric
D: Cut 1 in contrasting fabric - optional
E: Elastic, 1cm wide or narrower (enough for waist and both leg openings, depends on your toddler's size)
Dotted lines: place on fabric fold
Red lines = seam allowances
Grey areas = wrong side
White areas = right side
Illustration 1 shows how to place the pieces on the fabric fold (use a different fabric for piece D). However, there are better ways to do it if you want to save fabric.
Sew the heart or any other appliqué you like on piece A, using a zigzag stitch. Don't place it too close to the edges.
Cut your elastic. Waist: your child's waist circumference minus 3cm (I cut 42cm for my 3 year old).
Leg openings: your child's thigh circumference minus 1.5cm (26 cm for my 3 year old).
Assemble piece A and both pieces B as shown, sewing 1cm from the edges. If your machine doesn't have a stretch stitch, use a very narrow zigzag stitch.
When you're done, roll up piece A so that it stays out of the way.
Sew piece C as shown, right side facing up, 1cm from the edges.
Trim the seam allowances to reduce bulkiness.
Turn inside out.
Sew 1cm from the edges. Trim and finish sides with a zigzag stitch if you like.
Fold the waist edge as shown (1.5cm wide). Sew along the edge with a narrow zigzag, leaving a 3cm hole to insert the elastic.
Attach a safety pin to the elastic and slide it inside waistband.
Sew the elastic ends together, tuck it in and finish the waist.
Do the same for the remaining elastics.
Please note that the panties in the first pic were finished using a serger. With an ordinary machine and the zigzag stitch method described in the tut, it will look more like this (use a narrower elastic for a more discreet finish):