Foam Balls vs Repeating X-Bow: Which Refill to Choose
By CrunchLabs: Where kids & adults learn to Think like Engineers | Published: 2026-10-23
Category: Comparisons
Compare the Foam Balls Refill Pack and Repeating X-Bow Refill Pack for CrunchLabs Build Boxes. Learn which refill matches your lost part and build type.
Quick answer
Choose the Foam Balls Refill Pack if you lost balls for Trip Wire, Domino Catapult, or Ball Launcher. Choose the Repeating X-Bow Refill Pack if you lost foam rockets for the Repeating X-Bow build.
Why the right refill matters
CrunchLabs Build Box extras let you replace parts that have rolled away or launched into orbit. Each refill pack is designed for specific builds, so choosing the wrong one means the parts won't fit. The Foam Balls Refill Pack works across three builds, while the Repeating X-Bow Refill Pack is for one dedicated launcher.
Key difference: compatibility range
The Foam Balls Refill Pack is versatile—it fits Trip Wire, Domino Catapult, and Ball Launcher builds. The Repeating X-Bow Refill Pack is a single-build refill for the Repeating X-Bow only. If you have multiple builds that use foam balls, the multipurpose pack saves you from buying separate refills.
Trade-offs at a glance
- Versatility vs specificity: Foam Balls work with three builds; Repeating X-Bow works with one build only.
- Builds supported: Foam Balls: Trip Wire, Domino Catapult, Ball Launcher. Repeating X-Bow: Repeating X-Bow only.
- Price difference: Foam Balls Refill Pack costs USD 6.97 (was USD 9.95). Repeating X-Bow Refill Pack costs USD 6.17 (was USD 9.95). Both have free shipping in the US. The X-Bow pack is slightly cheaper, but the foam balls pack offers more build coverage.
Product facts
- Foam Balls Refill Pack (Build Box): Comes as a pack of 12 foam balls. Works for Trip Wire, Domino Catapult, and Ball Launcher builds. One pack covers three different builds, making it a flexible replacement for common lost parts.
Foam Balls Refill Pack (Build Box) - Repeating X-Bow Refill Pack (Build Box): Comes as a pack of 12 foam rockets. Refill pack for the Repeating X-Bow build only. If you own the Repeating X-Bow, this is the exact replacement you need—no guesswork on fit.
Repeating X-Bow Refill Pack (Build Box)
Which refill fits your build?
Best for
- Lost foam balls from Trip Wire, Domino Catapult, or Ball Launcher – choose Foam Balls Refill Pack
- Lost foam rockets from Repeating X-Bow – choose Repeating X-Bow Refill Pack
Not for
- Replacing parts for builds other than those listed – neither pack will fit
