A tutorial for cloning ready to wear boy-shorts

And now for some actual sewing. Well – pattern cloning, followed by pattern making, followed by sewing.

Following my (not very attentive) perusal of PatternMaking for a Perfect Fit by Steffani Lincecum (which I’ve reviewed here) I decided to clone some hipster trunks (read: boy-shorts for men) for my partner. My idea was to clone each of the boy-shorts I’d bought recently in really nice jersey and put some awesome contrast elastic* (thank me later) on top so he could have a rainbow of exciting underwear choices (as exciting as you can get without being kicked out of the men’s changing room at yoga/ making others feel too inferior). At this stage I had already traced out Kwik Sew’s**  K3298 boy-shorts so I could use them as a reference in case things went pear-shaped.

Download a pdf version of this tutorial here.


  •  I would recommend starting (if possible) with a brand-new pair (the best you can afford- you’re never going to pay for one of these again) of boy-shorts which have never suffered the seam-distorting effects of a spin-cycle.
  • A cork-board or thick piece of cardboard.
  • Push pins.
  • Large format paper.
  • Fine (fabric) pins.
  • Ruler
  • Pencil
  • French curve (you could use a dinner-plate at a pinch but curves are so inexpensive now that getting one is a worthy investment).

Step I

Lay your garment flat along a natural fold (indicated in Figure 1 by an orange bracket + arrow) and gently straighten any creases.

Lay the garment flat along natural fold.
Figure 1: Lay the garment flat along a natural fold.

Step II

Using the sharpest pins you have (I’ve used Clover’s extra long glass-headed silk pins indicated in Figure 2 by two orange arrows) pin the front and back together to immobilise the garment while you trace. You want to use as few pins as possible and try to avoid skewering the ‘knit’ fibres of the fabric i.e. Your pins should go through with no resistance- if there is resistance move the pin a little ways further from your original point and try again. This protects the integrity of your fabric.

Pin the front and back together.
Figure 2: Pin the front and back together.

Step III

Fold a large (=larger than the shorts) piece of paper in half and pin it (using push pins) onto your cork-board with the fold along one edge of the board. Lay the natural fold of your boy-shorts along the top. Be meticulous and precise. Use fine pins to gently pin the shorts onto the paper (indicated in Figure 3 by two orange arrows).

Align the edges of the paper and the garment along fold lines.
Figure 3: Align the edges of the paper and the garment along fold lines.

Step IV

Use a sharp fabric pin to gently poke holes through every seam and garment edge of the shorts (don’t forget to poke a ‘seam’ at the lower edge of the elastic where it connects to the fabric of the shorts). You want to make sure the pin goes through the fabric and into the paper below. These will become your garment outlines (seam and hem allowances to be added later). You can poke through hemlines at this point if you want.

Step V

Un-pin the fine pins holding the shorts to the paper and use your french curve and pencil to join the pinholes to make a pattern for the front half. Keep in mind that this is only half the pattern for one leg. DO NOT skip this step, once you’ve traced the back you’ll have two rows of pinholes and its good to know which is the front and which is the back!

Step VI

Flip the paper over and pin it back to the board with push-pins. Turn the shorts over and use the previously made pinholes to place its folded edge exactly over the fold in the paper. Use two fine pins (indicated in Figure 4 by two orange arrows) to pin the shorts in place. Use a fine pin to mark all seams and garment edges as before.

Align the edges of the paper and the garment along fold lines (back).
Figure 4: Align the edges of the paper and the garment along fold lines (back).

Step VII

Marking the grainline: lean in close to the garment (have a sharp fabric pin ready) and focus on one line in the weave of the fabric. Rest one hand near this line and use your pin to mark at least 5 pinholes along this line. Repeat at least 3 times with three different weave lines at 3 different parts of the garment. The reason for this is that not all of the holes will have lined up in each line and, statistically speaking, you need at least 3 points aligned to get a line you can trust. This will be the grainline for your pattern.


While marking out edges you may come across edges on the garment where the seam line (indicated in Figure 5 by an orange arrow) does not correspond with the fold line (indicated in Figure 5 by a blue arrow). In this case first pin-mark the folded edge of the garment, then using a ruler (Figure 5) measure the difference between the folded edge and the seam-line and add this amount to the folded edge indicated by pinholes highlighted in Figure 6 with red circles).

The distance between the seam line and the fold line.
Figure 5: The distance between the seam line and the fold line.
Adding the distance between the seam line and the fold line to the pattern.
Figure 6: Adding the distance between the seam line and the fold line to the pattern.

Lift off the garment and connect the pin-holes using a pencil and french curve. Label the front and back seams and crotch seams. Use a pencil and ruler to connect the pinholes made for indicating grainlines (all of them). Pick the best one and label it as the grainline.

Joining the remaining pin-holes and labelling everything.
Figure 7: Join the remaining pin-holes and labelling everything.

Step IX

Repeat the pin-marking for any other pieces that remain. Repeat the grainline marking process.

Repeat the process for any other pieces
Figure 8: Repeat the process for any other pattern pieces.

Step X

Transfer the pattern with seam and hem allowances to a new piece of paper. I use a Clover adjustable double tracing wheel (with bumpy edges not sharp ones)*** and black Carbon paper. Don’t forget to transfer the grainline onto your final pattern pieces.

The finished pattern with seam and hem allowances.
Figure 9: The finished pattern including added seam and hem allowances.

NB: When you make the actual boy-shorts remember to use fabric with the same amount of stretch as the original.

The finished shorts next to the originals
Figure 10: Admire your handiwork.

* Great quality (and awesome value for money) elastic can be obtained at Bedford Sewing and Knitting. I’ve used their bottle-green elastic for the boxers in this tutorial and their fancy blue elastic for making Jalie’s (2444 yoga pattern now, sadly discontinued) long tights and it has held up very well through machine washes (I put my tights into mesh bags before putting them in the machine).

**Looks like McCall’s have bought Kwik Sew [read: the Galactic Empire (BMV) is smashing the rebel alliance (non-BMV pattern companies)]. As a customer though, it might actually be useful to find Kwik Sew distributorship increasing (presumably being backed by McCall’s means Kwik Sew will now be available in every shop that stocks BMV patterns) and more Kwik Sew-specific sales with the kind of discounts BMV offer.

*** This is a cheaper version of the Clover double tracing wheel.

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