Note the scoring for folding the spider:
Rather than cutting out the entire spider and trying to fold up its spindly legs without accidents, the paper is cut away a bit at a time during the folding to provide something to grip, and make proper alignment easier.
Cut away the Vees of two opposing halves as shown:
Glue the first doubling fold, using the Vees to aid alignment:
Do the same for the other halves:
Cut away the last two remaining Vees and fold and glue:
At this point let the spider cure several minutes until the glue is really dry, otherwise the final trimming might pull the legs asunder.
When dry, cut away the last of the waste, then trim the legs thinner and with a little taper. The spider is printed thick in order to provide something to hang onto during the gluing - but it needs to be thin enough to slide into the propellor blades when finally trimmed (the little bugger is quite a bit smaller than an inch across, so this trimming is a bit of a delicate exercise):
Now glue the first blade onto the spider, and take care on two points:
1. Don't run the blade clear down the leg - leave enough clearance for the root collars of the other blades.
2. Give the blade some pitch relative to the spider (look down the length of the blade from the tip to set the pitch. About 20 degrees works well.
Let this assembly dry before moving on to the other blades.
When the other blades have been properly attached with their pitch set, your prop is finally down to one piece and looking more real with every step.
While I don't show it in the assembly photos, right now is the perfect time to glue a sewing pin through the center as a propshaft, if you want to have a spinning propellor.
Next chapter - the Hub Flanges