I haven't seen this particular version of fix on Instructables, just the 'my k-cup' fixes.
I picked up a "Solofill" reusable k-cup. It has a filter basket and hinged lid. The first couple times I tried it, the coffee was pretty weak. I did some extensive interneting, and found and modified a solution to get stronger coffee.
A commenter on Amazon noted that merely fitting a trimmed, used k-cup solved the strength problem, but for me, it did not solve the coffee sludge problem, so I made an extra, easy step.
There isn't really a clear 'how-to' otherwise on grind/packing/etc to get a good, strong cup of coffee out of one of these, so here we go!
The instructions on the solofill cup tell us that an espresso grind of coffee is too fine, and may clog the steel woven filter, so that's right out. I've tried 'drip' coffee grinds, but that comes out too watery for me. "Fine" grind, between drip and espresso works better, but leaves coffee sludge at the bottom of the cup.
What to do? TO THE BREAKROOM!
What you need:
A Keurig cup machine that allows the use of Solofill refillable cups
A solofill k-cup
Coffee drinking container
Finely ground coffee
Regular sized coffee filter
A used k-cup, cleaned
An extra, but not really necessary step is using filtered water, if possible. Either from a jug of spring water or from another pitcher filtered water source. It really does make the coffee taste better than using faucet water, depending on your location.
Step 1: Preperation
Once the filter paper is out, carefully cut the top edge off to the indentation and discard.
Using a teaspoon, or, really, anything else, fill the solofill cup 3/4 to the top, then tamp down firmly on the grounds, ONCE. If you tamp down everything very firmly, you may not get a full cup of coffee and you'll have to add hot water, more or less defeating the purpose of doing it this way. After tamping once, fill the cup the rest of the way up to the fill line, gently wipe the edge so no grounds are in the seal area, and close.
Take a regular sized coffee filter and cut into quarters. if you only have the smaller sized filters available, try halves, but you may have to cut off some of the bottom.
With the 'wavy edge' up, wrap around your solofill, holding in place, then insert both into the now clean and empty k-cup.
Step 2: Brew!
Just insert the whole contraption into your machine and let 'er rip.
Try to line the pre-punched hole up with your machine needle so it lasts longer.
When done, remove and toss the filter, but rinse and keep the k-cup sleeve. You should be able to use this several times. I got about 3 weeks worth out of mine the first pass before it got deformed and I had to replace it with a new, used k-cup. I don't know if this would work with the individual filters you can purchase on Amazon.