Due to the fact most crafts are done at home sat down its hard to imagine how you you can involve any weight loss into it.
Well you can.
Stand up to cut out and pin things if your back allows. I find I move about more back and forth smoothing this, pinning that, grabbing my scissors moving things out the way. I would recommend doing at a table not the floor or you’re tempted to sit.
Be prepared! Sounds like a 1950’s singer manual quote but honestly the more prepared you are the less distracted you’ll be more and less likely to stop for a ‘reward’.
Don’t sew hungry as you’ll be more tempted to snack in case of eating a meal because you just want to get this part done.
Don’t have handy chocolate or sweets near by. Provided you are prepared and don’t feel need to take a break because you have to cut something out or do this or that to continue you won’t find time to hunt out the snacks.
Get up for regular walks even if you run up the stairs to the loo. Loosen your limbs and don’t stay sat because no amount of not snacking or standing will help if you don’t take breaks.
In crafts such as crochet or knitting where you can’t move in the same way you could try standing up. Standing up takes energy strength and yes you can burn calories doing so.
If needs be a walk to the craft shop will suffice. Daily for extra effect.