You already know what I'm doing; making the longest range possible using a cantrip in dnd. (Please don't use this on your DM they will cry)

To start off, we have Greg here. Greg is a level twenty variant human aberrant sorcerer. They have the cantrip 'finger guns' from Valda’s Spire of Secrets: Player Pack. They have the finger guns cantrip, the spell sniper and sharpshooter feat, and the quickened and extended spell metamagics. Greg can shoot from 1200 ft, away (2400 ft, if we are using are metamagic), and the weapon's duration can be extended to 24 hours. This is using only a cantrip and they racial and class features. 

This is the Greg 5e stats:

 On each of your suggestions, we will add a future version of Greg, but more powerful.

Rules for suggesting:

1. Be kind, and don't say anything offensive (It will hurt Greg)
2. It must always have the last iteration's cantrip range or higher
3. It is allowed to make Greg overall better in non-sniping things
4. Only 5e is allowed. I will make a 5.5e Greg section if most people want it
5. It's range feature must use only cantrips
6. It can't take more than three actions to set up
7. It must be using official or non-official books featured in the DDB sources category
8. It can use items given the items follow all other rules

And so the Greg reign begins!

I'm not sure what the base range of 'Finger Guns' is, but a level 2 warlock can get an Eldritch Blast range of 300 feet (Eldritch Spear invocation)

The Spell Sniper feat doesn't work on Finger Guns because it doesn't have a range of at least 10 feet, it has a Range of Self.

Eldritch Blast 120 feet + Distant Spell (x2) + Spell Sniper (+60) + Eldritch Spear (+30/level)

Starry Wisp 60 feet + Distant Spell (x2) + Spell Sniper (+60) + Improved Elemental Fury (+300)

Valda's really is a big mess of nonsense, isn't it?

Quote from AntonSirius >>

Valda's really is a big mess of nonsense, isn't it?

 Yeahhhh

Quote from Plaguescarred >>

Eldritch Blast 120 feet + Distant Spell (x2) + Spell Sniper (+60) + Eldritch Spear (+30/level)

Starry Wisp 60 feet + Distant Spell (x2) + Spell Sniper (+60) + Improved Elemental Fury (+300)

 The circle of the land with the arid spell list gets fire bolt so you could do use that instead of starry wisp.

Fire bolt 120 feet + spell sniper(+60) + improved elemental fury(+300) + distant spell(x2)

The real question is order of operations. Does distant spell double the other bonuses too? If so then a land druid/sorc multiclass could have a fire bolt with a range of 960ft in 2024 rules. The Eldritch blast would be at most 1440ft with 18 warlock/2 sorc.

I'd say Distant Spell double the spell’s range originally.

Have you ever tried using Greg in a real campaign? I’m curious how using Greg in a real game would change the combat situations, the environment, or the DM’s reactions – are there any limitations in terms of rules interpretation?

Quote from ThomasFrank >>

Have you ever tried using Greg in a real campaign? I’m curious how using Greg in a real game would change the combat situations, the environment, or the DM’s reactions – are there any limitations in terms of rules interpretation?

 No, I haven't used Greg. Any DM I know would cry.

And depends what you mean on rules interpretation.