Just use some shrink tubing on the primary's solder tabs, that is sufficient to insulate the HV out of the way of curious little fingers, and inquisitive pets.
I started another compact sized amp, physically very similar to the12B4A SET on the left side of the photo:
The main differences is that it will use EL84s and a 12AT7, in a mutant variant of the "RH84" design.
Power trannie is the Antek 05T-240, I used the 220V tap for an approx 325VDC B+. Filter caps are 270 uF and 390 uF, with MUR4100A s in the FWB rectifier.
Got the power supply in the "tub" completed, and tested, and finished all the drilling and punching for the top cover, and mounted the OPTs, speaker binding posts, RCA inputs and volume control - and then, right on schdule, my back went "out" on me again, so it's all on hold until I can feel better and more able to work at the bench...
The other difference is that I mounted the round neon-illuminated power switch on the front of the "tub", rather than on the back as with the 12B4A, with the LED plot lite on the front. Just using what I have handy in the junque box.
/ed B