Yes with a little common curtesy to the rules of electrical safety,
a home made kiln should be safe.
Electricity, can not blow up! No way! It can of course spark a fire,
or cause an overheating fire.
Heat and drying over time is the practical danger. Generally,
unless properly [i.e. heavily] you need to have 12" to 36" free air
space clearance on all sides of your kiln. A crude rule of thumb is
if you can't hold your hand on any surrounding surface [vertical of
horizontal] it's over heating the kilns surrounding area. The
danger of too hot a surface is in the cumlative drying effect,
people misinstall wood heat equiptment and it can take 3 to 6+ years
till the house burns down due to the misinstalation. A sheet metal
shield is only effective if it has 1 inch of free air space, [the
sheet metal having the inch clearance on all 4 edges and both
surfaces] and that only reduces rated clearances by 1/2 to 1/3.
My purchased kiln [primarily for] glass fusing [Paragon SC-2] is a
high effiecency unit that stays hand holdable on the exterior even
throughout a 1500 F degree, 12 hr. cycle. But I spot check
surrounding clearance areas every firing cycle, I love fire and
flames, but only in her proper, safe place.
So, yes I have and will again use my own kilns for special sized
works, I will ere on the side of fire safety every firing cycle, I
like a professionally designed unit every time circumstances allow.
I don't want a visit by the fire squad, ever.
May firemen get very bored.