This is the first guide I've written, so go easy on me, im relatively new on Shaco too.

So, The way my build works is a bit of a Bulky Shaco when it comes to Melee attacks, the spell resistance is still a bit iffy (If you want/need, you can probably replace Trinity Force with banshee's Veil), but it works relatively well. The big thing is stcking Crit chance, some attack speed, and Armor Penetration on Shaco. Movement speed is extremelyfun on Shaco for Ganking easier, and the Armor is great for survival.

Boots of Mobility: The obvious Ganking boots to run across map for some Gank and Spank action
Infinity Edge: The AD it gives is obvious, and the increased crit chance is very helpful. But a huge reason for the Edge is the 150% crit damage instead of the 100%, as it also increases the damage of Shaco's Decieve ability.
Madred's Bloodrazer: Armor increase to help Shaco's survivability, Attack speed for more hits, and attack Damage for the same of Damage, and the Unique the same as every other persons reason, the extra magic damage to their health
Phantom Dancer: The movement speed increase helps Shaco get to and from Areas for ganking a bit faster, the attack speed helps to kill an opponent faster of course, and the Crit Damage stacks up even more for Shaco which can help do more crazy damage.
Black Cleaver: Attack speed increase and AD increase, the unique lowers opponent armor for Shaco to get in with some extra damage
Trinity Force: For me, it's USUALLY the last thing I would get, its useful but not exactly nexessary at the point of Late game. The AP increase helps a little bit with Shaco's abilities, Crit and attack speed helps, AD boost helps, and the unique helps when you, say decieve someone and get the extra damage on your basic attack, depending on who you fight, it takes a good chunk off the opponent.

Runes:
Greater Mark of Desolation x9: The obvious Armor Penetration that lets shaco do more damage
Greater Seal of Resilience x9: Adds armor to Shaco for survivability
Greater Glyph of Focus: Adds the Cooldown reduction to Shaco's abilities allowing you more usage in a shorter time.
Greater Quint of Desolation: Adds further Armor Penetration for Shaco

The skill tree I use is 21/9/0, grabbing all the Attack speed, Crit damage, and Armor Penetration abilities I can, and some extra damage dealing perks. Also, the rest is poured for Defense, giving shaco a LITTLE more magic resist, some Extra armor, and some Extra Health.

For Summoner spells, Flash is to help Shaco Chase players, or run from them if he's on the verge of death and Decieve to run just isnt enough. Exhaust helps Shaco take a few more hits from their lowered attack speed, and it slows them further for when he gives chase.

For now this is the guide I have, I may edit it when I have more time and get furtherly used to playing Shaco. Hopefully you all think my guide is okay, It's the first one I've made so I hope you guys like it a bit, and it helps you if you ever decide to try it in game, see you guys in the probable future :D