Your question is very vague and I'm not quite sure what you wish to accomplish doing this but here is my thoughts on this
As long as you are only doing this on your own network it is Legal and the dream police will not bother you
All of the stuff below is just an idea and a place to start using google.
Since routers use MAC addresses you could use a Packet crafting tool to create a packet or record a packet then replay that packet, I have played with Kali Linux on my network but have never tried this and I'm not sure how you would get any response since the packet is intended for another computer and that that computer has no idea why it is getting a ping response so it would normally drop it.
15 Best Free Packet Crafting Tools : : resources.infosecinstitute
You could try Arp poisoning.
You could read up about Man In The Middle Attack which uses as Arp poisoning.
The only way I know to accomplish what you would like to do is by running Linux and a good couple of hours reading, I run Kali Linux using VMware with 1 processor and 2 Gig of Ram.