Straight from the DMG Errata:
Attunement (p. 136)
The first paragraph ends with a new sentence:
“If the prerequisite is to be a spellcaster, a creature qualifies
if it can cast at least one spell using its traits or features, not
using a magic item or the like.”
emphasis added
Therefore, for the purpose of attunement:
If a creature is able to cast a spell by virtue of their own ability (not from an item), whether that be race, class, or feature, you are a spellcaster.
Simple enough...
Bead of Force: Creates a bubble of Force energy. You can roll it around like a hamster ball, and it only lasts for one minute...but anything inside only weighs 1 pound. Bear in mind, it deals some damage when it first goes off...so don't hit fragile targets with it. It is also expended on use.
Bowl of Commanding Water Elementals: Bit of an odd choice here, but Water Elementals have a native Grapple ability (Whelm) that they can use to constrain enemies
Cube of Force (attuned): Use to create a Cage Match if you get close to an enemy. For one minute, they are trapped within 15 feet of you.
Dimensional Shackles: Practically a Must if you intend to capture a spellcaster, as this is the most reliable way to block teleportation long-term.
Eyes of Charming (attuned): Charm Person is a great way to get people to willingly come with you.
Helm of Telepathy (attuned): Suggestion feature is also great for getting people to surrender and come along.
Immovable Rod: Put someone on their stomach, press one of these into the center of their back and push the button. They'll have a devil of a time getting their hands around to de-activate the rod, and they aren't getting up while it is pinning them.
Iron Bands of Bilarro: Fling a ball of metal at a target, and it restrains them. DC 20 Str check (once per day) to break free of it.
Iron Flask: Only works on creatures from a different plane of existence than the one you are on...but it works great for that purpose.
Mirror of Life Trapping: Not super portable, it's a 4' tall mirror, but...save or be indefinitely locked inside of one of 12 extradimensional cells. No escape clause except for someone letting you out. Keep this thing's command word a very closely guarded secret so no one can use it against you.
Rod of Rulership (attuned): As long as you haven't attacked this person, you can Charm them into thinking you are their leader...and then order them to come with you. It'll wear off in 8 hours, but by then...it'll be too late.
Rope of Entanglement: A rope that you can sic on people, and it attempts to tie them up.
Staff of Charming (Attuned): Again, magic people into coming along willingly
Tentacle Rod (Attuned): Doesn't exactly restrain, but it slows, gives them disadvantage on Dex saves, and seriously interferes with their action economy. They'll have a hard time resisting you in that state.
Wand of Binding (Attuned): Lets you cast Hold Person or Hold Monster...paralyzing targets makes them very easy to capture.
Wand of Paralysis (Attuned): Basically the same thing as a Wand of Binding
Wand of Polymorph (Attuned): Snails are remarkably easy to capture.
Wand of Web (Attuned): Fire restraints at your targets
Best Answer
Yes
Specifically, DMG pg. 141 (or here in the Basic Rules):
Since wearing two necklaces is something that I, as an Italian, had mastered at a very young age (right after making vowel sounds when surprised and slicking my hair back with far too much gel), it seems to me that an adventurer who regularly fights dragons, demons and the undead should be able to handle this without much effort.