I've cut the pieces out using a rotary cutter and a cutting board. The equipment is marginally more expensive than dressmaking scissors, but much easier and quicker to use. I've added seam allowances to the pieces as I've cut them - about 1cm to all the seams apart from the neckline, which I shall bind rather than seam, and a few centimentres to the t-shirt hem. I'm starting to think that the top might not be long enough, but I'll worry about that later.
First, I iron thin strips of lightweight interfacing to where the back shoulder seams will be. This will stablise the seams and keep the garment looking better for longer. Next I join the back and front pieces, right sides together, at the shoulder seam. USE A STRETCH NEEDLE for sewing stretch fabrics such as jersey or interlock. You can sew the seam using a straight stitch, but the seams are more likely to pucker and end up generally squiff if you do that - I always use a zig zag stitch or, even better, a stretch interlock stitch. The stretch interlock seam is sewn in a 'two steps orward, one step back' movement which keeps the seam straight and even. It sounds slow work but it's effective.
Next I need to bind the neckline. I was going to cut some ribbing for this, but couldn't find any with good enough stretch and recovery (i.e. pull the ribbing across its grain, and see how quickly it returns to its normal position) so I've used some foldover elastic instead. The actual sewing of
I sewed the foldover elastic using the same technique I'd use for sewing ribbing. I sewed the elastic to the right side of the neckline using a narrow-width medium-length zig-zag stitch, stretching the elastic as far as I could while sewing it. I then folded the elastic over to the wrong side of the neckline, and top-stitched it with a straight stitch, stretching both the jersey and the elastic slightly. The experienced seamstress will know that this is not a great technique for sewing foldover elastic - it worked on this occasion, but I was lucky to get away with it. Generally for sewing foldover elastic, I would sandwich the fabric between the folded elastic and just do one seam using 3-step zig-zag. What can I say? it was late and I wasn't thinking properly.
Next I pressed the neckline and was pleased to see that although it looks very odd from the inside - red thread against brilliant white elastic, yuk! - it looks just fine from the outside. I now sew the second shoulder seam (topstitching over the elastic binding as well as the shoulder seam) and then start on the sleeves.
First I attach foldoever elastic to the hem of the sleeves, using the correct 3-step zig zag technique. This gathers the hem nicely into the elastic binding.
I then mark the middle top of the sleeves and sew a line of long straight stitch around the top of the sleeve, starting from and ending at about 5 cm in from the sides. I pull on the bobbin threads to gather the top of the sleeve - this makes the sleeve puff up. I then pin the marked top of sleeve to the shoulder seam of the armhole, right sides together, and arrange the gathering so that the sleeve fits nicely onto the armhole. I do this for both sleeves and then sew the sleeves to the armholes using the useful stretch interlock stitch. This is the most fiddly bit of the t-shirt but it's worth spending the time to get it right.
When I've finished, I seam up the right sides of the t-shirt to the armhole, and keep going to join the two edges of the sleeve. Repeat on the other side of the t-shirt. it's then that I realise a number of pattern errors: the sleeve is miles too long and the body could do with being another 10 cm longer. These can be fixed: what could be more tricky is that the easy-fitting t-shirt style does not lend itself well to a puff sleeve! The sleeves look very odd and I think I'll leave it for tonight and see if I can dream up a solution.