#1
I have a 6505+112 that has no fuse cap. The amp was at a rehearsal place, turned it on and nothing. Went to check the fuse and it's gone!! The cap too. I have to play in 3 hours so how can I MacGyver it to work for the night? I have fuses .
#2
Go to your local electronics store/music store and ask. Even a TV repair shop may have one.

Your probably not using your amp tonight unless you find a replacement for it.
2002 PRS CE22
2013 G&L ASAT Deluxe
2009 Epiphone G-400 (SH-4)
Marshall JCM2000 DSL100
Krank 1980 Jr 20watt
Krank Rev 4x12 (eminence V12)
GFS Greenie/Digitech Bad Monkey
Morley Bad Horsie 2
MXR Smart Gate
#3
If you're truly desperate open up your amp and short across the fuse holder terminals.

You've just removed ALL protection from the circuit though, so if anything goes wrong it goes majorly wrong.

I do NOT recommend this, use at your own risk, YMMV, dry clean only etc etc.
“Ignorance more frequently begets confidence than does knowledge.”
Charles Darwin