Some discussion has started through the "Glad to be here" thread.

I'll be posting a complete list of the tools I've accumulated, along 
with prices and sources.

The best way to get started is to measure, measure, measure.  To do 
this you need gauges and a notebook.  I posted a data sheet I use in 
the Files area.  Its a MS Excel spreadsheet.

You must get a glass gauge.  These come with the kits or you can buy 
them seperatly from Babbitt (Jim Green 219-293-6514).  They were $15 
last year.  They come in a few variations: Narrow (like a reed width) 
or Wide (1").  Setback zero or Flush (zero is the edge of the 
glass).  Metric (2# = 1 mm) or Inches (1# = .040").  They do not 
offer all the different combinations of these variations, but they do 
have at least 3-4 to choose from.  I have the wide/setback/metric.  
The wide and setback supports the feelers nice but is cumbersome on 
soprano MPs.  I'm planning on getting a narrow one too soon.

It seems fairly standard in the US to us metric for the facing length 
and inches for the feelers and tip openings.

Feeler gauges can be found for about $5.  I got mine from 
SevenSaturdays.com for $3.95+1.50 s/h last year.  Just be sure you 
get a set that has a .0015" feeler in it.  Not all sets do.  For some 
of the larger feeler sizes needed to work on large tip tenor and bari 
MPs, I just taped 2 or 3 feelers together with electrical tape on the 
ends.  Not ideal, but usable.  You may need to combine two sets to 
get the intervals you want.  Just make sure the feelers are not bowed 
or bent.  You will get different readings whether they are pinched 
tight with your fingers or not.  I just use flat feelers (about 4" 
long).

Now the pricey tool.  You need something to measure the tip opening.  
I like using a digital caliper because it is also usefull for other 
measurements.  Mine was a gift, but I'm sure most are over $100.  
I've never tried a wand, but they probably work well and give 
repeatable results while using the same wand.

Paul Coats suggests trying to measure the very tip of the 
mouthpiece.  I think this is too difficult to do and not neccessary.  
If you use a wand, it seems to me that it would measure from where it 
contacts the mouthpiece on the inside edge of the tip rail.  I think 
this is a good place to measure the tip opening.  I hold the 
mouthpiece on the glass gauge and use the calipers to measure the 
distance between the glass (against the table) and the inside of the 
tip rail.  I do this about 5 times until I get what I think is a good 
reading.  By measuring from the inside of the tip rail, you can be 
off a little in how far you insert the jaws of your calipers into the 
mouthpiece.  To hit the tip of the mouthpiece is a lot tougher.

Tip rail width variations will effect your readings.  But I think 
this is manangeble.  Most of what I measure compares well to the tip 
opening charts.

Another suggestion: use your calipers to measure the width of your 
feelers.  Some of mine were off by .0015" and some were not the same 
from one end to the other.  This is another reason why you may need 
two sets of feelers.  Mark the actual size on you feelers if they are 
off.

The Winslow kit has .0015, .010, .014, .024, .034, .048, .063.

I ended up 
with .0015, .005, .0095, .0165, .0245, .033, .0485, .065, .079, .0955,
 and I could use some larger ones, like .125", for some of these 
mouthpieces that go up to .150" tip opening. 

I spaced out my gauges to where the intervals made sense to me.  This 
makes it difficult to share readings, but I have a computer program 
to assist in fitting a curve to the readings and converting the curve 
into whatever your set of feeler gauges you have.

Be sure to check out the files, photos and bookmarks areas.  I have 
put a lot of goodies in there.