Not to say it's a horrible build, because quite literally anything can be used on Zilean and can work so I am convinced I could make this work easily. My issue is that you're not getting the benefits of completed items. A full item is always going to be better or more beneficial than components. Building 3 Aegis's costs 3300 gold, gives 75 armour, 75 magic resist and 30 ability haste which on paper sounds great and for not a crazy amount spent. But Aegis can only upgrade into one single item which is Unending Despair and while the stats are fine, the completed items ability is useless for Zil. The other 2 Aegis's are just taking up spots for what could be more useful items. The 2200g you're spending extra for the other 2 could almost outright buy you a useful support item like Shurelyas (2200g) Redemption (2300g) Mikaels (2300g) or Imperial Mandate (2250) and every one of those is significantly more useful for Zilean than what 2 more Aegis's offer.

For a little while there I was doing a similar build where I rushed 3 Kindlegem's which only costs 2400g gives 600hp and 30 ability haste but those 3 gems can be turned into more than 10 different items to suit your need on a game by game basis. Essentially half building 3 support items for 1100g less than you're spending on 3 Aegis's which wont turn into anything.

Only other gripe I have is the match history you shared with the impressive win rate and K/D/A. Before I say anything else and because I'm inquisitive and fact based by nature, I am not trying to rank shame or be "mean" I guess (even though that's the way it's going to come off), but the account you're playing on is new (lvl 20 something) and those games are all in Iron elo lobbies, so while the match history looks good and the stats look good, it's pretty misleading because the quality/skill of players in those matches are pretty low therefore making this look better than it actually is. Especially if you're normally a considerably higher elo than Iron playing on a new account that you could possibly have ticked the "I'm a new player" box lol.

End of the day if you enjoy this build and the way you play, more power to you, but you should write a bit on here, let us know what the builds about, why you're doing it and how it works. To someone who's never played the champ they have no reason to question it, but as someone who's mastered Zilean, there's a lot of flaws.

Happy Zilean..en..ing. :D