I have an analytical balance. It is pre-digital age chemistry equipment. It is accurate to within 1/2 mg. At the moment, it weighs a 10 mg. calibration weight as 9.5 mg..
I mention this to point out there are other options out there, albeit I suppose these might be considered antiques by now, increasing their price... all I know is that I am very happy to have it (father was a chemist) and that the more I work with various chemicals, the more I understand why some folks cannot resist losing their objectivity on this topic and get very angry at eyeballers... some of these RCs are far more fluffy than others, my 2c-t-2 would literally appear twice as massive as 2c-i to plain sight of the particular chosen weight. It is so easy to be way off by 5 mg., it is not funny at all. I'll toss what I think is close to 12 mg. of 2c-d onto the balance, and lo and behold, it is 17 mg. ...
Given the spirit of harm reduction is to be objective, non-judgmental, and to divorce emotion from advice-giving to minimize harm when someone has decided they are going to do something whether or not it is very wise, I have tried to think up a novel form of advice for going forward without a good scale, and I am at a loss due to the fact that the compounds can have such different textures... I think the dissolved in solution method is probably the only way, but you had better do your dissolving and your conversion math properly.
All I can say in good spirit is that if you eyeball RCs, you are taking a very high risk adventure that may land you in a rubber room in restraints, a jail cell with some felony charges against you, a coffin, etc...
I know, but at first I was confused by the emotion this topic brings up in folks committed to harm reduction theory, now I see fit to add my opinion in support of such emphasis. The line between a recreational dose and an accidental overdose and poisoning can be a very fine line. Many adults lie all the time about relative risk and drugs, diluting the strength of trust between younger and older people. When we who are tolerant of moderate drugs consumption issue warnings, we should be trusted.