There are tutorials on how to spray synthetic cannabinoids on weed.
If the point is to make your weed stronger then this is the way to go. Some of the noids are more addictive than meth itself (check 5CL-ADB-A).
Meth needs higher dosages to make you high and people will smell it (you need at least 10mg to even feel it slightly), it will smell like ammonia (cat piss) when smoking it.
While 5cladba needs only 0.1mg to feel it and 1-2mg will kick you to the moon. Its not possible to smell 1mg of it. And its the same receptor in your brain aka. same drug category so it will result in more or less the same "kind of high". Meth will fuck up with your sleep so the user will notice it.
How is synthetic cannabinoid sprayed on cbd budz?
Start with about 0.5mg/budz for a strong high. You cant just "put the powder on the budz", you will have to dissolve it in ethanol. The concetration (mg/ml 5cladba/ethanol) depends on how thin/how much ethanol will be sprayed at once. Your spray bottle should be able to spray a small area and it should be very thin. Parfum spay bottles are perfect for this. If you use plastic sprays too often they will end up spraying much more liquid than they usually did.
Anyway a practical example: You only want to spray once per area*. Lets say your spray bottle sprays a circle area of 10cm^2 and lets say you can fit about 10g flat on that area, if you target is 1mg/g weed then the last step is to find out how much ml are you spraying per one spray. So you fill your bottle with eg. 10ml ethanol and you count how often had you to spray to empty it. Lets make it simple and lets say you needed 5 sprays to empty 10ml ethanol. In this case one spray has to contain about 10mg synthetic cannabinoids to fill our 10g cbd buds on 10cm^2 area. You will need a mixture of 5mg/ml 5cladba/ethanol and spray it once.
Dry it up afterwards (doesnt take that long) and smoke it, have fun. 0.5mg 5cladba/bud is about a average dosage and about as strong as normal weed.
* You want to spray once per area because ethanol will dry up the weed and potentially change the smell. You can overcome this by using aroma like terpines from real weed which are very expensive, cheaper is to use lemon aroma (and sell it as lemon haze). Obv. if you use aroma you need to recount "how often to I have to spray to empty 10ml" at the same concentration. You cant mix the liquids because 10ml water needs maybe more or less sprays to empty than 10ml ethanol. This goes same as for 8ml ethanol+2ml aroma needs maybe more or less spray to empty than 9ml ethanol+1ml aroma.