Custom class: Techromancer

Inspired by the Juggernaut post, I decided to post my own custom class I'm using in my campaign for some enemies. It is a custom class archatype for the Wizard:

Techromancer:

As a spell caster, you have decided to not only focus on the study of Arcana, but also machinery, and in doing so have learned how to construct machines to help you cast your spells in a more efficient manner. Techromancers find friends among tinkerers and architects, and often follow professions in which they build magical structures: Constructs, Magical Buildings, and magical traps.

Physics Instruction:
When you take this Archetype at level two, you learn how to read the language of other Techromancers. The time and gold required to copy a spell into your spellbook is halved. Blueprints are like scrolls, but for Techromancy spells.

Magical Tinkerer: When you take this archetype, you have begun to use machinery to make your spellcasting more efficient. Using 8 hours downtime (Cannot be during a long rest.) you can make a channeling pad from metal and a bit of your own magical essence. This channeling pad contains spell slots equal to half your wizard level (Rounding down), and can contain one spell its owner knows, and which it has spell slots for. The channeling pad is roughly 5x5 feet, and can be set up by using a major action.

While on the Channeling pad, and using the channeling pad's spell, you can choose to use the pad's spell slots instead of your own. Once the channeling pad is empty, it can be recharged during a short rest by expending spell slots equal to half the total number of spell slots the machine has, rounding up.

The machine's spell can be changed during a long rest.

Example: Robin is a 3rd level wizard, and decides he wants to contain a Channeling pad with magic missiles. He spends 8 hours to make a summoning pad with one 1st level spell slot, and which contains the spell magic missiles. During combat, he steps onto the pad and casts Magic missiles, draining the machine's spell slots instead of his own.

I've yet to come up with the rest, but the focus of the archetype is to be better at creating traps and setting up vantage points, rather than just going in guns a-blazing. Will edit once I've finalized the other class features.