Instead of scissors to create opening on cut to fit, has anyone used a "cutter tool" such as the ones by Nu-Hope or Parthenon?  Or even a craft cutter tool? 

If your stoma is a  nice round circle, and not strangely shaped,  use a gasket punch. They can be purchased on ebay and amazon.

The set I purchased when I first got my ostomy 7 years ago, came with several cutters from 20 to 40mm in size. I have been using a 35mm cutter for the last 3 years.

I cut a month's worth of wafers at a time, and store them in a ziplock bag to keep them fresh.

Edit: Also, some ostomy supply outlets will precut your wafers for you, often at little or no cost, so you might check into that too!

Click the link below to see a photo of the die cuter I use:

but I'm 77 and not quite as steady so get slightly uneven cut.  Hence looking into cutter tool.  Not big deal, just looking to make things one bit easier. 

You actually do bring up a valid point, so I can absolutely see how a cutter may be helpful to you.

The Nu-Hope cutters seem to be reasonably priced, so it might be something to try if you have access to them. 

I have been using pre-cut for many years (ostomy in 2005!).  But very small change in size at base of stoma of late (or noticed of late) has allowed some seepage under adhesive with skin irritation.  Upon remeasuring, I find a 28 or 29 mm size would be best for me.  Hollister's Cera Plus is best for my skin, but only offers 25 mm or 30 mm in this range hence, cut to fit.  I use curved scissors which work fine, but I'm 77 and not quite as steady so get slightly uneven cut.  Hence looking into cutter tool.  Not big deal, just looking to make things one bit easier.  Thanks. 

There are a few things to note, however, which convinces me that cut-to-fit is still the best way to go:

1. Stomas can change size, even years after surgery. The investment in a cutter may be for nothing if that happens, although, you can still buy different sizes for the punch.
2. Not all stomas are perfectly round. A cutter will leave some extra gaps around the stoma, which may not be ideal.
3. As with #2, cutting the wafer tends to result in a more accurate fit. 

But as @bago says, a pre-cut wafer might also be a good option if your stoma is round and consistent. 

Just open the package and put it on. No cutting with any device.

I can see that if you have an oval stoma that you could do multiple cuts with the circle cutter to get an oval shape.