There are basically 2 different rivet styles, and several materials. Primary rivet styles are Flat Head (AN426) and Round or Button Head (AN470). This picture shows a 3/16" diameter Flat Head and a 5/32" Button Head.
The AN numbers are the most common, but you might also find them called out by Mill Spec number:
Flat Head = AN426 = MS20426
Button = AN 470 = MS20470
These numbers call out the configuration of the rivet.
There are multiple materials available for rivets, and they cover the range of useful materials, from soft to very very hard (Secs say vary vary, I guess for emphasis).
Stossel hulls normally use Medium Hard rivets specified as "AD" (AN426AD, AN470AD). "A" rivets are soft and "AD" are medium hard. "D" "DD" and "DDD" rivets are progressively harder and higher strength, but also more likely to fracture from impacts etc. So the 2117-T4 rivets are 38,000 PSI tensile strength vs. 72,000 PSI for the 7075-T6 hull material and 36,000 PSI for the stainless cap. That's correct, the hull material can handle 2X the load of the SST rake cap, but the cap is stiffer.
Note that they list shear strength values too. Shear strength is just what you think it is, the metals sliced in half because the mating parts moved. Shear strength is always less than tensile strength, but if a fastener fails in shear, the connection has already failed. The purpose of any fastener, rivet, bolt etc. is to compress two or more surfaces together. The compression results in friction between parts that resists movement, adhesives improve on this (see next post). If the mating parts move, the friction drops so all the sudden the fastener sees a shear load and will eventually fail.
The point is that the mating parts are not supposed to move, the connection tensile strength and proper tightening are the critical values. The rivets are supposed to pull two or three pieces of metal together nice and tight and keep it that way.
It is also worth noting that 7075 aluminum gets it's strength from a high copper content. Beyond making welding impossible, the copper makes this the most corrosive grade of aluminum and is the anode ("-"), which corrodes away just like the negative terminal on the start battery. The 304 SST Rake cap is the most noble ("+") material and is the cathode, which actually gains material in the corrosion loop. 2117 Aluminum rivets are a good bit less corrosive than the 7075 hull sheeting ( and a little better than 6061). Ideally the rivets would be the most noble, but we settle for less than the hull, which has way more area to corrode/consume over time vs. the small area of the rivets, which are in direct contact with the SST. If we went harder on the rivets they become more anodic ("-", corrosive) and can become the focal point of corrosion.
Rivets are a pretty basic Aviation commodity, they are not outrageously priced. Monroe in Melbourne is a local source, Aircraft Spruce is a national source.
Aerospace Rivets | Monroe
Rivets | Aircraft Spruce
The last part of the part numbering is the size. Rivets are specified in 32's of an inch on diameter and 16's of an inch on length. So these bags hold AN426AD (Flat Head, Medium Hard) rivets, 3/16" diameter (-6), 1/2" and 5/8" long (-8 & -10). Note that flat heads are measured from the top of the head as they are intended to be countersunk below the surface of the mating (SST) surface.
For the -8, 1/2" rivets, we are joining 0.100 thick hull sheet to 0.062" SST cap. So that is 0.16" grip length and 0.34" (~3/8") length to be compressed during riveting. For the -10, 5/8" rivets we have the added thickness of the 1/8" patch plates used in the last rebuild, keeping the exposed head length the same. General rule of thumb, thickness of the materials to join plus 2x rivet diameter, +/-