So I brought Trundle the other day and of course I started to do the trundle jungle because why not =]. Here is my basic build for him

Items

Starting items - Cloth armor 5x Health Pot

Wriggle's Lantern - standard jungle =]

Boots - Mercury Treads

Phage - wither build this into Trinity Force (dmg) or Frozen mallet (Surv)

Youmuu's Ghostblade - or if you going more survival just get The Brutalizer as cool downs are the way to go

Sunfire cape/force of nature - get either one first depending on team set-up

Warmorgs / Atmos impaler - want more surv get wormorgs want for dmg get Atmos

this is just a general item guide i don't go for all of them directly but all of the items work for the trundle jungle

Runes

Ad Quints

3x ad red

6x Arp red

9 x armor yellow

9x magic resist blue

Masteries

depending on what you like more tank go defensive more dmg gos offensive that easy really =]

Over all thoughts

Jungle trundle is superb as he is turns out to be a great off tank and damage soaker in the later game he can also turn a tank into a squishy and turn squishy's into nothingness =]