The long scale (26") Stringmaster needs a case at least thirty-six (36")inches long.

Nominal dimensions:

Neck lengths:

22-1/2" scale = 32-1/4" long
24-1/2" scale = 34-1/4" long
26" scale = 35-3/4" long

Width of D-8 is 9-3/8" at bridge end and 8-11/16" at headstock end.

Width of T-8 is 14" at bridge end and 13" at headstock end.

Width of Q-8 is 18-1/2" at bridge end and 17-1/4" at headstock end.

(Width dimensions could vary slightly depending on tightness of through bolts concealed under "diamonds".)

Each neck of a Stringmaster is ~4-11/16" wide at the bridge end and ~4-5/16" wide at the headstock end.

Neck thicknesses are inside to outside - 1-1/2", 1-7/8". 2-1/4", and 2-1/2", respectively. Bridge covers and knobs are nominally 1/2"-9/16" high.

Bottom of guitar body (leg side) to top of volume and tone control knobs and bridge covers. (Height needed inside of case)

Inside neck - 2-1/4"
Second neck - 2-1/2"
Third neck - 2-3/4"
Outside neck - 3-1/4" (Q-8 only)

John

Length: 35 1/4"
Width: 8 7/8" (4 3/8" per neck plus the gap between necks)

This guitar is a true rectangle with no taper in width from head to bridge.