General aviation pilot reported that while entering the traffic pattern at a Class D airport; they made an evasive turn to avoid what they believed to be a UAS. The aircraft landed safely with no damage.

Narrative

I was on a short flight from GEU to ZZZ and back to GEU. I was approximately 6 NM inbound for return to GEU and asked to report base to 3 miles final expecting a small 45 degree entry to base for long final Runway 19. At approximately 4.5 NM I was asked to slow for another aircraft entering a right down wind (heading in my direction) for Runway 19 GEU; at that time I was at 110 kts and slowing towards 90 kts and at about 2;500-2;550 ft AGL. Traffic pattern altitude is 2;100 ft AGL. Tower asked me to widen and slow further despite now being at 2;300 ft AGL and 95 kts to keep distance from aircraft now turning base. At that time I looked left to my 10 o'clock horizontal and saw what appeared to be the aircraft just beginning base; at that moment I had a few other objects in my line of sight (very clean clear windows); one looked like a possible helicopter of some sort but very small; maybe 3 to 4 feet in length and similar height; kind of zoom by; that combined with the plane turning base kind of close for my safety; we called making right 360; I tipped my right wing up briefly to check approach area I was about to enter; to my 12 o'clock horizontal to my 5 o'clock and my passenger did the same; two never spoke to another aircraft other than myself and the plane in the pattern; the area looked clear and told Tower right 360 again (2nd time); no response; I initiated the right 360 to avoid perceived close aircraft; ZZZ1 airspace and outer north edge of GEU Class D; due to the hazard to the safety of my continued entry to the approach at that moment; I felt at that time. Under the circumstances of another moving object in my sight with the plane in the close foreground may have lead to my very unusual evasive action that was as I think on it after landing that it was not only very stupid but in itself could have caused an incident/accident had there been any other aircraft there. I just felt from perception of the smaller object/craft?? very nearby that I could have collided with that craft or it was the plane turning base. My haste in that decision and not having full communication with two could have lead to a lapse in perception and judgment; with good intentions for safety when in reality it was unnecessary. I do fully accept this lapse in proper action/judgment; fortunately it was quiet in the area and I understand the scope of the hazard I created by that. I have clean history and want to take remedial flights in and around that area with a CFI to get much more on top of the serious business of GA flying especially in the crowded training airspace in and around ZZZ2. I apologized to the Controller for my snappy passenger and the potential hazard created by avoiding a hazard that was avoidable. I can not stress enough how important safety of flight and my future in aviation is and that this avoidable experience has made me. It will never happen again unless it is emergency. See and avoid has been a top priority in this airspace. As stated I will conduct remedial CFI training flights and ground of at least 10 hours and maintain currency to my past high standards. Flying weekly there after. My future within the part 91/135/121 means the world to me. ATC may have contributed; however we made two (two calls to Tower about the right 360 prior to engaging that turn). I still own up to the poor/stupid call on my part for the maneuverAny further questions please contact me.