Admittedly this is only handy if you sew (whether by hand or machine) or can talk someone who does sew into it...but here's a fix.
I needed a lightweight house robe for a man, but that's hard to find...the thrift shops are closed at the moment, most at the stores are at least flannel, and online most are for colder climes. Figured I could cobble two pj shirts together into a decent one, but I'd also need to enlarge them to make a decently large robe. I really didn't want to accidentally ruin two new shirts if I overestimated my abilities, so I researched how others might have handled the problem, then tried it out on an old favorite but inexplicably shrunken robe of mine.
Basically, you make side panels.
|Open the side seams of your top|
So, here is my scruffy cotton kimono-esque robe. You can use this trick on shirts, t-shirts, simple dresses, whatever you can get away with.
Open the seam that runs up the side of the shirt/robe, from the edge of the sleeve to the bottom of the hem.
And of course do that on both sides, assuming you're into symmetry. If there is no actual seam, you can just cut it open, but try to do it as straight as you can or you will have a much more interesting top than you planned on.
I used a seam ripper for a while, then got impatient and cut the rest along the seam. (It's a very dull seam ripper)
|Side seam being opened|
Next you will need to find a long panel piece of fabric, preferably of the same type or weight as the rest of the shirt, and hopefully something that will go with your shirt (either matching the color or pattern, or complementing it). Unless you don't care, then go with whatever you can scrounge up.
So to do this, you need to estimate how much larger (width-wise) you should add to your top in order to be able to wear it comfortably. If it almost fits, maybe you just need a couple of inches of scoosh space. If it is very uncomfortable, maybe you need 4" or 8" of added material. If it is ridiculous, just turn the shirt into a pillow.
Say you need 4" of space. You need a little extra room to sew a seam on either side of the panel as well. You will have two panels (one on each side of the shirt) so you will divide this by two.
So if you wanted beefy half-inch seams, you'd need two panels of 3" wide material, for example.
Or 2-1/2" strips, if you use the standard quarter-inch seams.
|Adding a side panel strip|
If you don't have anything that long, no problem, just cut short strips and sew them together into one long strip.
If you're going to do this properly and nice, you should pay attention to line things up with the weave of your material, or create the strip on the bias. But if you're just slapping it together or it's a t-shirt, this'll do fine.
You can hem the edges of your strip up first to match your top (where the sleeve starts and where the garment ends at the hem) or you can leave that for later and match it up (or hem up the whole thing). I left mine for later.
Anyway, with the garment inside-out, pin the strip from the sleeve edge (if you haven't hemmed it, let it hang out enough to hem) down to the bottom garment edge/hem (also leaving hem room if you haven't already hemmed it).
|Pin panel strip along seam line|
|Both edges pinned down (sleeve end). There is a pieced seam across this |
part of the panel; when you sew the panel in, try to have the seam flaps
either open or aimed down toward the bottom hem...just feels nicer.
|Whole side of panel strip pinned for sewing|
You should baste it in, just in case you need to do some serious altering, like if you sewed it in the wrong way round or it is way too big or way too small, etc. And you'll need to see if it fits okay around the sleeve.
|Basting one edge of the panel to the top.|
|Basting in the other seam of the panel strip.|
Nothing like having to rip a tight seam out again. And again...
|Do the other side of the garment the same way.|
When you get one side done, do the other one, or you'll be unusually avant garde. Or at least breezy.
|Top with side panels inserted.|
Ta da, you have new girth to your garment! See if it fits ok. If it doesn't, you'll have to alter it a bit or live with it. If it does, go back and sew the seams in with a proper sewing stitch so your work doesn't fall out when you wear or wash it. Then you'll need to finish off the seams in whatever way suits you...if you're lazy, just leave them be. Otherwise you might want to iron them open, or zigzag trim them with pinking shears, or serge them, top stitch them into place, or get fancy with a french seam...whatever. I haven't done any of this yet, so my robe here is all puffy and wrinkly, but, you get the idea.
|Longer shot of robe with side panels.|
Don't forget to hem the panel ends --the sleeve and the bottom hem bits. You can either do just the panel section (carefully) or you can turn the whole hem under, add seam binding to hem on, use lace, etc. instead, whatever you like.
Anyway I think I can handle making a robe now. Hope you can figure any of this out! Share/show your results if you try it!