This answer presumes that the desired effect is "ball bearings/claymore mine" and that fireball was the best you could come up with. I'll offer that there is something else available if you allow for other game items as a solution set.
Exam question: How do we get animate object into the rogue's hands, or into the hands of a fifth level party generally?
Option 1: Claymore with the Wizard participating (risk of failure)
A scroll of animate object, one time use, with the risk that since the Spell is 5th level, and the wizard is 5th level and can thus only use up to 3rd level spells, the attempt may fizzle since there is a chance that the scroll won't work. Rogue places ball bearings, wizard casts animate object from the scroll, and if DC 151 roll is made, claymore carnage proceeds as below.
Option 2: Claymore for a 5th level Arcane Trickster Rogue
If your rogue is an Arcane Trickster, then he can use wands since at level 3 the rogue acquires the spell caster feature. Otherwise, the rogue needs to wait for level 13 to use magical devices. Your wizard can use his fireballs for other challenges to the party. Or, the wizard can use the wand, as the scroll above but with no chance for failure.
Caveats:
A wand usually requires attunement, and you'd need to have such a wand arrive in loot/trade/treasure/whatever. This means that you'd have to be OK with offering a rare magical item to your player at level 5. This might be early in terms of level/magic, but it's not too far out of the box. (See DMG rarity guidelines on magic items/treasures, there are a some rare items for Tier 2 play, page 135; rare is listed for character level "5th or higher")
Not all wands require attunement by a spell caster, although the one I used as a model does. You can choose to have the proposed wand require attunement, but not require "by a spell caster" so that any rogue could use it. If you leave the attunement as shown in the original wand, then the wizard would be able to use it in any case.
Reskin the Wand of Binding to be the Wand of Animating
The Wand of Binding holds 7 charges, and can use 5 of them to cast the 5th level Hold Monster Spell, or the 2d level (2 charges) hold person spell. (Recharges 1d6+1 charges at dawn) Spell save/attack DC 17 (requires attunement by a spellcaster) (SRD p. 248)
It becomes a comparably powered item called
Wand of Animating which has 7 charges; casting Animate Object (5th level) uses five charges, casting Levitate (2d level) uses two charges. (Recharges 1d6+1 charges at dawn) Spell save/attack DC 17 (Optional: requires attunement by a spell caster)
Why Animate Object?
Animate Objects 5th-‐‑level transmutation
Casting Time: 1 action
Range: 120 feet Components: V, S
Duration: Concentration, up to 1 minute (This allows you to delay!)
{snip} Choose up to ten nonmagical objects within range that are not being worn or carried.
I think we can safely call a ball bearing a tiny object. :)
{snip} Tiny, +8 to hit, 1d4 + 4 damage (Table in spell description)
{snip} If you command an object to attack, it can make a single melee attack against a creature within 5 feet of it. It makes a slam attack with an attack bonus and bludgeoning damage determined by its size.
Here's your claymore:
Put 10 ball bearings on the ground, in a bowl, in a helmet, or whatever suits your rogue.
Use the wand to cast animate object and then (here is the delay part) when the time is just right, command the ball bearings to attack. You have up to one minute, depending upon how long you delayed. The text says that an object can attack a single creature, so this as much a "shotgun" as a claymore. However, you can get the "pattern" effect if you as DM interpret the spell to allow each ball bearing to attack any creature within range ... I can see that going either way for this application of that spell. (You are already home brewing a bit, so why not?)
The wand wielder rolls 10 "to hit" rolls. For each ball bearing that hits does 1d4+4 damage. A max possible 10d4 + 40, but he'll probably miss a few ... and if a few crit, so much the better!
The above procedure makes the claymore mine usable once per recharge cycle. (Unless the recharge cycle d6 roll stinks)
Final Caveat: as @Szega notes, one reading of this spell text is that
the ball bearing can make one attack for as long as your caster/wand
wielder can concentrate on the spell. That would make this much more
lethal than a "one shot blast" since each ball bearing could attack
for up to 10 rounds. If you feel that is too powerful, you can
reduce the number of rounds that the ball bearings can attack, or, you can go
ahead let it be awesome claymore carnage for that one big blast of the
adventuring/recharge day. The limiting factor there becomes whether or not the rogue or wizard can maintain concentration. As the players go up in level, the HP of opponents will tend to handle the damage better, which is part of why I made the earlier caveat about rare items and character levels. (A scroll is the more conservative approach).
I added levitate as the 2d level spell for the wand since it seems thematic to moving things around with magic. It isn't necessary to be on the wand, and could be removed without harming your desired effect of a claymore making method using what's available in the rule book, with a slight tweak.
Note: I totally stole this idea from a player in our game whose wizard does exactly this with ball bearings and animate objects. He's 11th level. Our DM rules that they all attack at once, which I like to call "the shotgun blast" effect. But "personal claymore" works fine. :)
1 From Spell Scroll (DMG):
If the spell is on your class’s spell list but of a higher level than
you can normally cast, you must make an ability check using your
spellcasting ability to determine whether you cast it successfully.
The DC equals 10 + the spell’s level. On a failed check, the spell
disappears from the scroll with no other effect.
