Here is a simple datapack that allows you to use copper to build beacons. 
Since copper blocks oxidize, the only stable blocks are fully oxidized blocks:

Oxidized Copper
Oxidized Cut Copper

and all waxed blocks:

Waxed Block of Copper
Waxed Exposed Copper
Waxed Weathered Copper
Waxed Oxidized Copper
Waxed Cut Copper
Waxed Exposed Cut Copper
Waxed Weathered Cut Copper
Waxed Oxidized Cut Copper

Only these blocks can be used.
You can also use a copper ingot to activate the power(s). You won't see a copper ingot in the beacon GUI next to an iron ingot, gold ingot, etc, but don't worry, it will work.

You can also use me Amethyst beacon and you can use both at the same time

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I encourage you to check out other datapacks that I have published:

Archaeology with hadron
Let"s loot some chests with hadron
Skeleton skull from the nether
Magma cream from slimes
Geode massacre
Real Hero of the Village
Alternative bartering
Amethyst beacon
Copper beacon
Vein mining
Miner's dream datapack
Dig perimeter with one hit
Upgrade your wither skeleton farm farm
A little easier spire armor trim template and piglin's head
Enderman killed in the nether gives eye of ender
Diamond Geode
Cutting Vanilla, Terrestria-and-Traverse-wood