Modified in three steps:
1.The first step is to modify the top rail Mount

2.Second step is to modify the ButtStock

3.Third step is to modify the Fore-End

You can find the item sold on Amazon:

 https://www.amazon.com/dp/B07FNH3F78

You can find the item sold on JgcWorker website:

https://jgcworker.com/products/jgcworker-f10555-3d-printed-cj-001-kits-set-for-nerf-zombie-strike-zed-squad-longshot-cs-12-blaster