It is well known that you are not allowed a pace stick until your testicles have descended. Until then, you are only allowed to carry a drawing of one, neatly folded, in the top left-hand pocket of your combat jacket.
Whilst imagining my forthcoming (and unfortunately never realised) promotion to WO2 (CSM) CBO I did a little investigation into this matter and contacted an old colleague, a former CRSM from the Royal Army Tailoring Corps. His advice was simple, and based on the triangulation principle. Stand, with your feet apart, and at an angle of 45 degrees. Open the arms of the pace stick until both points are central to each of your toe-caps - at this point the apex of the stick should just touch the third button from the bottom of your No 2 Dress flies, although a little leeway in either direction is acceptable.
Then, without changing the settings of the pace stick, extend both arms from the side of the body to an angle of 45 degrees and, with the help of a colleague place the points of the pace stick central with the nail of your index fingers - at this point, the apex of the stick should just rest under the mid-point of the peak of your No 1 Dress hat. If it doesn't, the simple fact is that you are not cut out to be a CSM and should perhaps seek employment with the QM.
A tried and tested method, and one successfully introduced, and still used to this day, in the Trucial Scouts.
I recall the Guards Depot armourers used to have a nifty little earner in pace stick production for participants of the drill courses - amazing what you can make out of a MOD broomstick and some old brass shell casings. Dunno where the course is run now but it should'nt take someone long to find out. But, I would think someone there is still in the pace stick business and would be willing to help a potential customer.
The storeman there has a sizing pacestick from Ammo & Co along with order forms. A few of the guys on my course earlier this year went to John Bull so they could get them instantly (from the cases they look like their from Dancraft )
With John Bulls discount they work out a little bit cheaper than Ammo's but I think Ammo & Co throw in a free desk stand if you order from them so if you want one of them too it's cheaper to go there.
Can't comment on the quality between the two as I haven't bought mine yet, but the Wing Sgt Major seem happy enough with the John Bull (Dancraft?) ones during a room inspection