Okay, I'm attaching the TIFF fin patterns for the Estes Magnum to this 
message (two attachments -- let me know if your mail program doesn't 
handle that right).  The fin stock is 1/8" thick, semihard balsa -- quite 
decent wood in this kit.  Prime Number Explorer uses 3/32" fin stock.

Tube measurements for the Magnum and Prime Number Explorer are as 
follows:

Magnum:

Booster:                                  70 mm     2 3/4"
Sustainer:                               458 mm    18 1/32"
Payload coupler (exposed portion):        10 mm     0.394"
Payload tube (clear BT-60):              127 mm     5"
Nose cone ogive (to 2mm radius meplat):  212 mm     8.346"
Launch Lug, 3/16":                        50 mm     2"
Motor mount tubes (both)                  70 mm     2 3/4"


Prime Number Explorer:

Body tube:                               343 mm    13 17/32"
Motor Mount Stuffer:                     229 mm     9"
Nose Cone (to 3mm radius meplat):        126 mm     4.96"
Launch Lug, 1/8":                         60 mm     2.36"