It is quite possible to make blimp envelopes yourself, but I never reached the helium tightness of industrially made balloons. Also the “valve” used by commercial balloons is hard to match in ease of use and tightness. Therefore I based my project on ready made balloons:
Two Zeppelin NT foil balloons, available at the webshop from the Deutsche Zeppelin Reederei.
A 52” blimp envelope, as common for toy RC Blimps. I actually used a 52” x 37” version with extra load bearing capacity. This allowed to add more trimming weight and removing it to compensate for helium loss over time.
A 36 or 38” round foil balloon (as sold for toy RC “flying saucer” blimps or large decorative balloons).
About 2 to 3 m2 of balloon foil (I used a type with one side in white, matching the main hull, but a silver coloured Enterprise Z would look great too).
The last to items could be replaced by an "Amazing Indoor Anti-Gravity Flying Disc", if you can find one.
Similar flying discs are available, but these are smaller and come in colourfull prints not suited for this project.
99%+ pure helium for maximum buoyancy. For small quantities I find it cheapest and easiest to have my balloons filled at the local balloon shop. Balloon Surprise in Drongen gives excellent service.
Some extruded polystyrene sheet (mostly known under the brand name “Depron”, about 0.5 m2 of 5-6 mm thickness and 0.5 m2 of 3 mm thickness.
about 3.5 m of 2 mm diameter glassfiber composite rod (as available from kite shops) or, even probably better probably about 1.5mm carbon composite rod.
Polystyrene contact glue. The clear type is preferred, but as I didn't have that available some camouflaging was done at the end with white acrylic paint.
Clear cellotape, wide and standard
Thin double sided tape (the carpet fixing type).
A printer and paper (as light as your printer accepts is best, but I used ordinary office paper)
About 50g of plasticine as trimming weight (no play dough, as this tends to dry out and lose weight)
Propulsion and control:
The propulsion and RC components should be under 40g. I used an 8g parkflyer receiver, three 6g micro servos, an extra motor from such a servo, a 10g LiPo battery and three 6.5 diameter indoor airplane propellers. To that I added , two small gears with a 1 to 3 ratio (4 is even better), some 2mm diameter carbon rod (a piece of 20 cm and one of 40 cm), an a extra small micro switc and about 2.5 m of the thinnest isolated electric wire I could find.