The plastikov is a receiver for an AK pattern rifle. Plastikovs used to require very specific (and unusual) AK parts kits but as of v3 they've expanded to act as a pretty decent general purpose AK receiver frame. The maker is IvanTheTroll, the scene is Gatalog.
The initial plastikov was more a proof of concept than anything as most people believed that the action of an AK precluded plastic receivers completely.
https://odysee.com/@TheGatalog-PrintableFramesReceivers:9/Plastikov-v3.0:0
https://ctrlpew.com/file-drop-the-plastikov-v3-3d-printable-akm-rpk-ak100-receiver/
https://3dgunbuilder.com/rifles/plastikov-v3/