The EEVBlog µCurrent hasn't been in stock for quite some time and who knows whether Dave has the time/energy to setup another production. Because of this I'm thinking of simply having my own µCurrent made however looking at the BOM, I've noticed that many parts are actually no longer available.
Has someone created an updated BOM which will nearly meet the original specs?
The main critical part in the µCurrent is the max4239 AZ-OPamp with a good bandwidth and low offset. Everything else should be easy to replace with different parts / manufacturers.
For the resistors one has to see what is available at a reasonable price. The search functions at the suppliers should help here.
For the µCurrent there is sometimes the misconception it could be a good solution for small currents. For the really small currents (e.g. < 10 nA) the better solution is often a transimpedance amplifier configuration and using a more normal (non AZ) amplifier.
IFAIK the lower current ranges have no protection with clamping diodes - I would add that option to a PCB if I would build a version.
Ideally one may want more shunts (e.g. 1:10 or at least 1:100 steps) to choose from. The current solution is OK for some currents, but not for all. The 1:1000 steps are just to large to cover everything in between. It would also make sense to have a case with no shunt and thus the option to use it as an amplifer for low voltages (e.g. a thermocouple).
The nice point is having DC accurate gain with low offset. This may help to add low burden current ranges to a DMM, but is less important when used with a scope. With a scope one has a DC offset from the sope anyway and noise is often more relevant the the offset.