Over the last couple of months I have struggled with drafting a toddler cap sleeve. For whatever reason, my infant cap sleeve came off without a hitch. I tried some quick and dirty pattern making by grading the infant sleeve up to 24M and using it as my toddler base. The shaping just didn't work and I had to actually draft a 3T sleeve. I used the opportunity to compare draft instruction between
Aldrich
and
Armstrong
and these are my results.
The actual draft instructions for either cap sleeve are fairly simple and easy to draft. Even so, I didn't like the shaping and resultant styles of either sleeve. I'll try to explain the differences of each. I had a stronger preference for the Armstrong version, but I still modified hers considerably.

The top sleeve is the Aldrich version, the bottom my modified Armstrong sleeve. The Aldrich sleeve is very straight - such a sleeve results in a large sleeve cuff opening. Her sleeve is not a fitted cap sleeve. The instructions were easy to follow, I just had a styling disagreement.
I much prefer a fitted cap sleeve. The basis of the sleeve draft must start with a regular sleeve block. Just draw in a style line similar to what you see in the photo for the shaping at the hem. There are some minor refinements detailed in the Armstrong book. The problem with the Armstrong draft is that the sleeve cap height was too high for a toddler. I decreased the cap height by about a good 1/2". Walk the sleeve cap along the armscye and adjust any length differences. Armstrong states there should be 1-1 1/2" of ease in the sleeve cap, which is simply too much. My sleeves have virtually no ease because I removed it. Sometimes the fabric calls for 1/4-1/2" of ease, but not anymore. A sewing operator will return a bundle with too much sleeve cap ease. It is just too difficult to sew in an industrial sewing. And in IMO, it doesn't do anything for fit or wearing ease. Armstrong's draft instructions are easy to follow and you can make any adjustments you prefer after you have the shape you want.
If you look closely, you will notice that my sleeves are symmetrical. This is because my bodice armhole shapes are identical for the front and back. This is typical in the industry for infant and toddler styles. In older children, this is not true and Aldrich's basic sleeve drafts illustrate the differences very well.
Kathleen Fasanella has blogged much on the proper shaping of sleeve caps.

Here is a sewn sample. On the right is the Aldrich cap sleeve and my modified Armstrong sleeve is on the left. Can you see the difference in the sleeve shaping and cuff openings? The sleeve on the right is good for t-shirts and casual styles. The sleeve on the left is better for more formal, fitted styles. I have a few minor refinements to make and at least one more sew test and I will have my toddler cap sleeve done! (I am debating on adding 1/4" back to the sleeve cap height, overall I like it).
Either book will get you a basic cap sleeve. My eyes prefer the fitted style. Any questions? Anyone need draft instructions?