I went to visit my granddaughter for a few days but I was reading the forum
Material: 3 mm okoumé ply so far is pretty strong and my Agilo has been getting some beginner driver abuse...
Poplar ply should be much lighter, I can't say anything about it because I have never built anything from poplar ply in my life (a long time...). The plywood man was here on a visit just before I left and we talked about the different options - you can buy poplar that is just as dense (heavy) as okoumé, it depends on the trees the ply comes from. You can have okoumé as dense as birch for the same reason. With wood density = dimensional strength.
With Agilo build clean and you will save weight, excess epoxy does not bring more strength (well not everywhere). I could probably sand off about 200 grams of epoxy from mine.
I managed to cut most parts to within 0.5 mm tolerance. If you want a perfect Agilo cut perfect wheel well sides. Mine are too large, I cut outside the line instead of on the line. That part (for me personally) defines how well the rest of the build goes together.
I have built lots of boats and Agilo was an "easy" build. Despite mine being the very first and a couple of places I did not follow the building instructions correctly. You will never know where because all the time I was feeding back information to Bodo Sitko and the plan and building instructions were adapted or made more clear. I also made mistakes because that is what older builders do
Lack of concentration and just plain dumb sometimes.
And the result is a vélomobile I feel secure enough in to drive downhill at over 70 km/h. The more I drive the happier I am, I hope it works out that way for all the other builders/drivers.