I love making boxers and briefs from scrap fabric for using any small pieces of leftover jersey from larger projects. I find I can usually squeeze a couple of pairs of small briefs out of a piece of fabric after having made a t-shirt or similar, keeping us well stocked in comfortable underwear.
Sometimes, to fit even a small pair of children’s undies into the leftover fabric I have to get a bit creative with the cutting. Sometimes that means that the pattern placement might be upside down (not too noticeable with his fabric, because which way up is space, anyway?), or I may even have to introduce an extra seam in. Generally I wouldn’t put a seam into the back of a pair of underwear (due to discomfort) but I am happy to add side seams where there were none initially. These Waves & Wild Speedy Pants boxers do not have side seams in the original pattern, but by introducing side seams it allows me to cut the boxers out of a narrower offcut of jersey.
Another benefit of introducing side seams to this pattern is that it allows a second front piece to be added into the inside with fully enclosed seams for comfort. It is a fiddly manoeuvre as the whole of the two front side pieces have to fit, rolled up, into the centre panel pocket, using a very narrow burrito style roll method. These boxers are the Age 8 size. There will be a point in the smaller sizes at which the boxers become too small to make the manoeuvre feasible, but it will work for this size and larger (and certainly for adult boxers of this style).
I also like to fully enclose the gusset section of the Waves & Wild Speedy Pants briefs. Though these are designed with he gusset to be left open (pocket style) in the briefs view, I do not find this as robust, tidy nor (through having pairs of briefs myself designed this way) as comfortable, so I make an enclosed gusset for these also.
I usually make a modified enclosed gusset when making this pattern, where I cut the pieces exactly as given and use a ‘fold and flip’ method for the front gusset insertion seam, but I modified the pieces this time, cutting both gusset pieces separate from the front as this allowed me to complete the entire project on the overlocker (the ‘fold and flip’ uses a small three step zigzag stitch on the sewing machine) and, to be honest, I just forgot.
I will document these modifications, for myself as much as anything, so I can always refer back to them should I need to jog my own memory. Comfortable, soft underwear for kids with kind-to-skin bands of soft jersey rib really does make every day better, and there is no better way of using offcuts than by making boxers and briefs from scrap fabric