My glider used to have a panel behind the spars which meant nothing could fall into the fuselage and foul the aileron & air brake connections. We have no idea when it was lost, but it's not there now.

We want to make a replacement, but the easiest and IMHO best way to fix it safely is using the attachment points glassed into the fuselage. The parts manual I have makes it clear these are some sort of Dzus fasteners but not a clue as to what size / length, or indeed what exact type if there is more than one! (I have no idea about the later question).

Can anyone help, please?