BPA Tools!
Below are a few tools which will help you analyze bloodstains.
Drafting Caliper
My instructor showed us how to measure stains by using drafting calipers.
Magnifying Loupe
A loupe will help you in seeing those very small stains of 1mm and less and they come in different magnifications. The one shown is 10X.
Protractor
No doubt, a protractor comes in handy to determine the angles needed to string a stain. An ordinary one or perhaps one with a laser attached. You can also find a half protractor like the one below.
If you like to string your patterns, then you'll like this elastic A few good rulers are a must for measurements and
string which can be found at most craft and fabric stores. for your photographs.
The use of templates can be helpful in training the eye to visualize particular degrees and the true ellipse.
Not pictured here, but you'll also need a good scientific calculator.