This website shows some stumbling stones every Sonex builder will encounter. The purpose is that once a follow-builder starts riveting a part shown here, then better stop, think twice and probably find a suitable way to complete the job.
Hard or impossible places to set rivets (Sonex-Ltd how did you do it?)
This is the rear of the aileron. The two parts extending the aileron are the attach plates for the counterweights. There is only 8mm lateral freedom between center of the hole and the attach plate - much too few for any commercially available riveting tool (at least on this side of the hemisphere).
This is the elevator drive horn. The encircled rivets are solid ones, bucketed from the opposite side using an angled rivet set. Properly setting blind rivets per the plans here is impossible.
Rudder drive horn prevents setting these rivets.
These rivets can be set, but forward horizontal tail spar is in the way, so rivet puller cannot be held perpenicular which leads to badly set sivet heads.
This is the attach point for the flap drive. The pivot plate restricts access to these three rivets.