Some design elegant weapons, you just like blowing stuff up. Your designs don't need to look like much as long as they function. You don't need to spend years studying, you just find what works for you and run with it. Function over form, you use Dexterity to cast the spells associated with each of your inventions (rather than Intelligence as an Artificer would) as a credit to your skill as a sharpshooter.

Level 3: FWOOSH!

You gain access to an incendiary device that replicates the effects of the Burning Hands spell, which you can use a number of times equal to your proficiency bonus per short rest.

Level 3: SKITCH!

You gain access to a firearm that replicates the effects of the Magic Missile spell, which you can use a number of times equal to your proficiency bonus per short rest.

Level 7: KA-BLAM!

You gain access to a thrown device that replicates the effects of the Blindness/Deafness spell, which you can use a number of times equal to your proficiency bonus per short rest.

Level 7: WHIZZ!

You gain access to a device that replicates the effects of the Continual Flame spell, which you can use a number of times equal to your proficiency bonus per short rest. You may choose to hold the object or launch it up to 30 feet in any direction.

Level 10: BOOM!

You gain access to a firearm that replicates the effects of the Fireball spell, which you can use a number of times equal to your proficiency bonus per long rest.

Level 10: ZAP!

You gain access to a conducted energy weapon that replicates the effects of the Lightning Bolt spell, which you can use a number of times equal to your proficiency bonus per long rest.

Level 15: WHUMP!

You gain access to a containment device that replicates the effects of the Otiluke's Resilient Sphere spell, which you can use a number of times equal to your proficiency bonus per long rest.

Level 15: ROAR!

You gain access to an incendiary device that replicates the effects of the Wall of Fire spell, which you can use a number of times equal to your proficiency bonus per long rest.

Level 18: CRASH!

You gain access to an inspiring command that replicates the effects of the Passwall spell, which you can use a number of times equal to your proficiency bonus per long rest.

Level 18: BWOOP!

You gain access to a communications device that replicates the effects of the Rary's Telepathic Bond spell, which you can use a number of times equal to your proficiency bonus per long rest.