For the first jet pack ill try to explain on what to do
1 leather strap = 4 leather and 2 iron ingots= line 1 leather iron leather / line 2 same
1 flux capacitor= 3 red stone 2 lead ingot 1 sulfur and 1 quadruple battery= line 1 blank red stone blank / line 2 lead ingot quadruple battery lead ingot line/ 3 red stone sulfur red stone
4 lead ingot
2 lead stone thruster to make this is a long process first step you'll need bronze armor plating= 2 blaze power 1 red stone 2 steel plate 1 glass 2 titanium plate = line 1 titanium plate glass titanium plate/ line 2 steel plate red stone steel plate/ line 3 blaze power blank blaze power now the next step you'll need invar plate you will need 2 chrome plate and the bronze armor plating same set up as step 1= line 1 chrome plate glass chrome plate /line 2 steel plate red stone steel plate/line 3 blaze power bronze armor plating blaze power now you'll need Enderium armor plating same set up as step 1 and 2 but you'll need signalum plate and the invar armor plating now to make the leadstone thruster same set up as 1,2 and 3 but you'll need 2 Iridium alloy plate and the Enderium armor plating
now to make the jet pack line 1 lead stone ingot flux capacitor leadstone ingot/ line 2 leadstone ingot leather strap leadstone ingot/ line 3 leadstone thruster blank leadstone thruster
there's your first jet pack