Virgin Build ?

I have some experience changing guitar pickups, pots, etc. but that's about it. Eager to learn more and try a pedal build.

Question is, what is a fun entry-level pedal build to get my feet wet before I become an all out addict?

I don't necessarily need a clean boost but I've been looking at the BYOC Confidence Booster. Seams pretty straight forward.

The BYOC kits are pretty good from my limited experience of 2 builds. If you can make a decent joint go with a basic dirt box. Very simple circuits and BYOC instructions are easy to follow. I skipped the confidence builder and went with "slow gear" for my first build. Super easy.

You might consider an A-B box. I suggest that because another plan might be to re-house two effects into one and use the A-B switch all in one enclosure. For instance, two DS-1 pedals set differently can be useful to switch between them.
You might also want to consider simple mods to existing pedals (like the inexpensive and plentiful DS-1). You're probably pretty good at soldering by now, but schematics and symbols may be new to you so start with your weaknesses and build on them.

I built the BYOC A/B Looper. That was pretty easy. I also did the general guitar gadgets 60's Fuzz Face. The directions were not clear (they were for the PNP positive ground version), but I eventually figured that out and got the pedal done. It was my first effect pedal. I like it. I refused to build a pedal I didn't want just for practice.

A/B/Y box is a good option. I have 2 amps so I could run one or both. Hmmmmm?

My strictly personal opinion is that you shouldn´t pick modification of a commercial pedal as your first project.If you build a preamp,overdrive or something else that isn´t too complicated you will learn far more and if we consider the worst case,a pedal that doesn,t work the chance of fixing it is bigger .If you screw up a BOSS pedal you haven´t learned how it works and you may have destroyed an expensive pedal.