This stackable grenade body is based on the Marine Corps prototype Scalable Offensive Hand Grenade.

The device is intended to be assembled before or on mission for an appropriate amount of force. On paper the device can be used as a less lethal option due to the plastic case and low fragmentation when one is used, while the extra amount of explosive of a second unit attached becomes unquestionably and no longer 'less lethal' though there is no point at which any of these would be safe. A further third charge is intended or rumored to make the device capable of destroying infrastructure.

In the ideal situation, one device thrown into a building which you have encountered fire from will make everybody inside reconsider their actions and walk out with their hands up. Two of these can be used as a lethal grenade to ensure activities cease. A third one is going to ensure activities do not occurr in this area code and any surprise gifts left behind will go unopened, because maybe you already have a grenade in a glass jar waiting for you on your door frame at home.

In reality, there is no appropriate amount of high explosive to use as a less lethal option compared to a traditional flashbang, and an explosion thats simply bigger, is not garunteed to be lethal in all environments with no shrapnel. At the third option the device is cumbersome, and the end user may find themselves regretting their choices given the large effective range compared to the short distance it can accurately be used. The thing we can be sure of is that the idea probably looked incredible in the DOD power point otherwise they wouldn't have got the funding.

Now that the project has gone nowhere, it is ample inspiration for a device that I recommend you use as a smoke grenade only. There's no maximum limit to the amount of smoke you feel like making somewhere so long as the end result is what you intend and it is not malicious to traffic. The plastic body is sure to easily release pressure and is unlikely to fragment or travel with any force, whilst allowing all manner of smoke generating compounds to flourish. 

I am not certain what occurrs if colors are mixed, and I dont recommend storing varied colors assembled together if used for singaling purposes.

While a smoke grenade is generally not a dangerous item provided you are aware of the fire risk, I am not liable for any sword fights that occurr. 

A prototype fuse and spoon is included, and M228 style hammers and springs are necessary.