Unless, you do the maths yourself to find the correct angles there aren't too much you can do for now to be spot on. Mecabricks currently doesn't handle this case - No bones or IK systems.

OK, thanks! Is there a way to get dimensions of particular pieces? I can calculate the position of the studs on the 2x2 plate using your guide on modeling parts, but, for this example, I would need the length of the holder (probably from the center of the hole to the center of the clip), and for the 1x2 plate, the distance between the two shafts.

Nevermind, I was able to figure it out.

The holder itself is two studs long (16 units) (center of hole to center of clip). On the 1x2 plate with shafts, the distance from, e.g, the center of the left stud to the center of the left shaft is 8 units. Therefore, forming the right triangle, the angle needs to be 30 degrees.

A trickier one was for the legs involving element 3839 (Mini Handle). The shafts on the sides of that one actually turned out to be 6.4 units from the stud, which I found by snapping a 1x1 plate to the shaft to get its coordinate. Then forming this triangle, the angle turned out to be asin(0.4) which is approximately 23.578 degrees.

I found when adjusting my model that just by eyeballing it, I was really close anyway (in the first case, I was off by about 1 degree, but in the second case, I was within 0.1 degrees 😃 )