My 'sewing kit' consists of a 1"x2" piece of light poster board with black, white, beige, red , blue and yellow thread wrapped around it (like the ones they USED to have in hotels), 2 needles stuck into it, 2 buttons that match hubby's pants and shirts, a few safety pins, and small nurse's bandage scissors (blunt tips, good small blades and not curved like nail scissors). All goes into a very small baggie. Takes almost no space and weight is minimal. I have used this to repair clothes, shoes, day bags, even umbrellas.
Same for first aid kit. A baggie with assorted band aids, a few seri-strips or butterflies (have actually needed these), a few packets of anti-bacterial gel and a few of cortisone gel (moved from 3-1-1 bag after security), a couple of 2x2 gauze pads, a tiny roll of adhesive tape (paper kind that tears easily), chap stick (it works for paper cuts, dry cuticles, bug bites and other things as well as dry lips) and a few alcohol wipes. You could add a bit of moleskin if wanted. Again, it is very small and takes up very little space. I take extras of some things in my 'big bag'.
As for the duct tape (or masking tape or cellophane tape), I have read of many uses here and think it might be wise to have some (but I don't agree with putting it on your skin to protect against blisters- the adhesive is NOT designed for human skin and could cause problems- just take mole skin or use band aids). One suggestion someone once made- don't take even the whole mini roll. Take a very short pencil or a pen cap and wrap a few inches around it (can do the same with the adhesive tape above). You want to take just enough to get you through an emergency (a hole in your bag or sole of shoe coming off, etc.). That will give you time to go buy more, or make other 'repairs' later.
I now put our daily meds in individual 'pill pouches'- tiny baggies you can get at your pharmacy. So Monday's AM meds for me go in one, lunch meds in another, then repeat with Tuesday, etc.. I also have a few Over The Counter meds that we use regularly- Aleve, Dramamine (hubby needs sometimes), Benadryl, antacids, etc. in other pill bags. All the pill bags go together in a baggie (mine in one, hubby's in another, OTCs in a third, then all into another. Each day I put that day's meds and the OTCs into my day bag, along with my inhalers. I also have to take a few hard candies- I am pre-diabetic and sometimes my blood sugar drops and I use them to deal quickly with that.
I also take a small 'nail kit'- small clippers, tweezers, and emery boards (not metal files). The clippers can sub for scissors if needed, plus hubby is always asking to use them to clip hang nails, etc. Emery boards have extra uses, too. This also goes into my day bag.
ALL of this takes up very little space and does not weigh very much at all. Every bit of it has been used multiple times on our trips. I don't take enough to stock a health room at a middle school- just enough to get us through an emergency until we could buy more, or to save having to hunt something down.