The SIG Sauer P320 (M17) pistol replica is already available. Soon, a conversion kit made by SRU Precision will also become available, which transforms the pistol into a PDW type weapon. Like most products of this manufacturer, the SR-PDW-320 is made using 3D printing technology.
All the SRU Precision projects are very eye catching. Here are just a few examples.
M4 conversion kits
AKM conversion kits
One ones dedicated for pistols:
HiCapa
HK Mk.23
Glock (GBB and AEP versions) conversions made for replicas by different manufacturers
Beretta M93R (GBB and AEP versions)
There is also a stock for the VSR-10 rifle replica
Conversion kits are available, among other places, on the manufacturer's website: https://www.sru-precision.com
Photos: SRU Precision