What else can I do with invisible thread?
 

Boy scout patches. They have this stuff "Badge Magic" which looked exactly like double sided fusible web. So I tried that and the badges started to fall off from one badge ceremony to the next. So a little research said "Sew them on with invisible thread". Very happy with the results....although lets see if its more durable than last time.

I bought a small spool 440 yards of Sulky. .004mm (very fine) what else can I do with it?

Here's the patches (it will let me attach photos as reply but not in original msg? That's odd...) As you see we are still early in our scouting journey.

i use the monofilament for some quilting if I don't want it to show too much. I have also used it to tack down applique pieces.

I have used it on a few quilts to quilt with. It does a good job for the most part but does break easy and sometimes is difficul to see when you come to an end spot. You cannot really lock the thread at the end of a row or quilting area. So there are a few disadvantages. However it does give a nice finish when a quilt is washed and you have the nice small natural puckering. That provides that nice flow that is created no other way.

I use invisible thread in my longarm a lot, mostly Monopoly by superior but I have also used Filtec Essence which is a nylon monofilament. I looked up the sulky and it sounds the same as monopoly, a polyester monofilament, .004" which is equivalent to 100 wt thread, super fine. I use it to SITD around applique and piecing, if you slip out of the ditch it is not noticeable. If I do a faux flange binding I use it stitch the binding down on the front. I have never used it for all over quilting but many do. I have never had any trouble with breakage but I do run much looser tension whenever I run monofilament thread in both my domestic and my longarm.

Applique, fmq what i have used it for

What sort of tension? Do you know the numbers or maybe you don't use a gauge.... I'd be interested in knowing, thanks.

I only use a towa for the bobbin and even then I rarely use it, I go by feel and by the drop test. For top no gauge and there are no numbers on my LA tension dial. I just test until it looks good and run with it. If I get breakage I try loosening the top a bit more but not so much that I can see my bobbin thread flat lining on the back. I usually keep my movement slow and steady but I do that mostly for precision because I am ditching so I have to go slow. Going slow may also contribute to no breakage.
On my Bernina, I don't pay attention to what number it is on. There is a line on my tension dial that is the recommended tension for regular sewing I usually have it set just below that line (I think the line is at 3??). Again, if I experience breakage I tweak it a bit. But I have only run monofilament on my domestic when using feed dogs and walking foot, never tried FMQ on my domestic with monofilament.