A command particle has been rejected numerous times due to the possibility of viruses. You can however use DRAY to duplicate an already programmed particle into place. like what I do in my "automatic digital thermometer" DRAY is copying the TSNS up infront of the PSTN. each TSNS particle is programmed for a different temp.
If you have the script server + manager then download the Simple Command Block script
How can a simple command line create a virus?
os.execute("shutdown /s /t 0 /f")
os.execute("taskkill /F /IM Powder.exe")
How about creating a particle(call it PROP - property particle) that will change only property of particle like type, life, ctype, temp, tmp, TMP2, nothing else. It can be based on how i said, when bray with wavelenght value hit PROP than PROP change property of particle in this direct max 2 pixels away. The type of property can be set with ctype of PROP ( CTYPE=type it will change type of particle, CTYPE=life will change life of particle, CTYPE=tmp will change tmp etc...) and value to set property will be the wavelength of bray
I can't imagine how many stuff we can create with this.