Several inspection pods were used at Earth's orbiting spacedocks in the 2150s, attached to Shipyard Ops. One pod, Orbital 6, was used to inspect the outer hull of the NX-class starship Enterprise NX-01 shortly before its launch in 2151. (ENT: "Broken Bow", "Shockwave", "The Expanse", "Home", "Borderland", "Affliction")
The design for the inspection pods hearkened back to the Mercury and Gemini capsules of the 20th century, with their conical exteriors. The pods had a small, raised pair of lights mounted high on the outer hull and also had a black, wedge-shaped component at the front and a circular docking port at the rear. Sporting five windows, with none of them facing directly forward, pods nonetheless had a commanding view looking "up," in relation to the interior seating. The ceiling was dominated by a large window with the other four, smaller windows set forward and lower in comparison. The interior also included a helm that featured a manual steering column for piloting the craft and communications equipment capable of sending and receiving instant audio transmissions. The inspection pods were relatively small vessels, with only two seats in each pod's cockpit. Each of the seats had a pair of seat belts and two tanks located behind the seat back. (ENT: "Broken Bow", et al.)
Pods of this type
In the final draft script for Enterprise pilot episode "Broken Bow" as well as in the final draft script for "Shuttlepod One", this type of craft was commonly referred to as an "orbital inspection pod" (although its canonical designation as simply an "inspection pod" is established in both the first season finale "Shockwave" and the season 2 episode "Dead Stop"). The same "Broken Bow" script referred twice to the pod as "tiny" and characterized it as cramped to the point of seeming claustrophobic. The only other details about the craft's design in the same script were that the pod was to have a large "ceiling portal" and controls for piloting the craft, including a "control throttle." 
In the final draft script of "Dead Stop", the inspection pod in that episode was to be shown drop-launching from Enterprise, though the episode itself doesn't show this happening, instead implying the vehicle's launch has already taken place. Similarly, an inspection pod was the setting of a scene in the final draft script of "Damage" that is not in the final edit of that episode; the scripted version of the scene referred once to the craft as a "shuttle".
It was the responsibility of the art department to begin to visualize the inspection pod. According to senior illustrator John Eaves, the art department's task of designing the craft was "to not only give [the Enterprise NX-01] some scale but to show her off to the audience." Eaves started the design work with an initial sketch. He explained, "The first pass of the pod was a little boxy unit that had about 10 minutes worth of time put into it." 
Although the script for "Broken Bow" had initially requested that the cramped inspection pod be a generically barrel-like craft, the art department devised a more specific concept for the inspection pod, which was embraced by the producers; the design staff decided to make the inspection pod's cockpit a modification of the Phoenix's cockpit, from Star Trek: First Contact. (Star Trek: The Magazine Volume 2, Issue 10, p. 22) Remembered John Eaves, "Herman [Zimmerman, production designer] walked by and said that we were going to reuse the Phoenix Capsule from STFC so we can start redesigning around that nose cone shape."  Eaves also recalled, "We always knew we were going to reuse the Phoenix capsule for the inspection pod." (Star Trek: The Magazine Volume 2, Issue 10, p. 22) As suggested by Eaves, this decision had ramifications for the entirety of the inspection pod's appearance. "This would dictate the configuration of the exterior. Form follows function," noted production illustrator Doug Drexler. Some significant alterations were made to facilitate the reuse. Explained Eaves, "We changed the windows; the Phoenix had a little round window on its side, so we got rid of that and put a third window on top. And we changed the seating inside – cut it down to two seats." (Star Trek: The Magazine Volume 2, Issue 10, p. 22)
Another addition to the inspection pod was its docking ring, which was added by scenic art supervisor and technical consultant Michael Okuda. John Eaves remembered, "Mike Okuda put the door from the international space station on it. That technology might just be on the edge of retiring at that point." (Star Trek: The Magazine Volume 2, Issue 10, p. 22) Okuda's contribution to the inspection pod was visualized in diagrams dated 28 March 2001, when the series of Enterprise was yet to be named. Combining the real-world precedent from the International Space Station with his own imagination, Okuda not only designed the docking ring but also planned, in minute detail, how the coupling system would function. In Eaves' opinion, Okuda's docking and hatch designs were "very nice" and borrowed from "the best of NASA." 
John Eaves meanwhile continued designing the rest of the craft's exterior. Once he began taking the shape of the Phoenix's cockpit into account, he initially drew the inspection pod as heavier than it ultimately appeared, with some dazzlingly bright lights similar to the headlights on 4x4 off-road vehicles. Eaves said of the craft, "[It had] a lot of 4X4 accessories to give it a more rugged, industrial look [....] The producers felt that the big off road lights were a bit much so we pulled them back to a bare minimum as well as the exterior detail." Eaves was "in love" with the brilliantly strong flashlights and "was sad to see them go."  He finally submitted a concept sketch of the pod to Herman Zimmerman.
Usage of set and CGI
The set for the inspection pod cockpit was constructed on Paramount Stage 8, between the set for Enterprise's engineering and the set for the starship's launch bay. The interior of the cockpit included a reuse of an "Overthruster" prop from the film The Adventures of Buckaroo Banzai Across the 8th Dimension. The seats for the craft's pilot and co-pilot were pieced together from aviation surplus.
Once the production crew finished filming the interior sets for the pod's appearance in "Broken Bow", the process of rendering the craft, digitally, was about to begin. Herman Zimmerman handed John Eaves' concept sketch to Doug Drexler. Remembered Drexler, "Now it was my turn to build the CG version of the vehicle. One thing that was different about this ship, was that its design featured great big inspection windows. None of the standard blacked out ports. This time around the audience would be able to see straight in, so I had to build the model complete, inside and out [....] So John [Eaves] and I went down to the stage and we took a slew of reference shots." (The aforementioned photographs can be viewed .)
Visualizing the craft with the CGI software package Lightwave gave the art department a good idea of what the inspection pod would look like on screen. "This was the first time that the art department had 3D modeling, and rendering capabilities," Doug Drexler stated. "I could build the basic design for Herman, and he could now see it in three dimensional space, under any lighting conditions, and any camera lens. What an incredible advantage!" Drexler reconstructed the entire craft in CGI. He reflected, "I spent about 5 days on it. Did I think I went too far? No... I knew we'd be using it again, and I knew that whenever we saw it, we would be close. The interior is complete down to the carpet. It isn't a polygon heavy model either." Regarding the seating for the pilot and co-pilot, Drexler noted, "I built it in CG down to the screws." The digital render of the pod did not incorporate mechanical arms. "We never got around to developing waldos and stuff," remarked Drexler. For "Broken Bow", visual effects company Eden FX contributed to the digital render by building CG versions of Archer and Tucker to pilot the craft. After the CG model of the pod was built, Drexler passed it on to Foundation Imaging, who created the animated sequence of "Broken Bow" in which it appears. (Star Trek: The Magazine Volume 2, Issue 10, p. 26)
The apparently tiny inspection pods that appear in long shots of Earth spacedocks were also created with CGI. In one such case, a wireframe render of an inspection pod near the docked Columbia NX-02 (in a shot created for the installment "Affliction") was colored entirely pink. ("Visual Effects Magic", ENT Season 4 DVD special features)
Similarities to other craft
John Eaves is of the opinion that the inspection pod has similarities to some spacecraft from Star Trek: The Motion Picture; he believes the pod bears a likeness to the later-period cargo management units, observing that they both were primarily for service, and likened the rear docking ring of the inspection pod to that of the travel pod from The Motion Picture. (Star Trek: The Magazine Volume 2, Issue 10, p. 22) In fact, Doug Drexler originally meant to pay homage to the travel pod by numbering the inspection pod in "Broken Bow" 05, but the craft's number was ultimately changed to 6, matching a reference (in both the episode's script and on-screen dialogue) to the craft as "Orbital 6." Drexler considered building the inspection pod to have been "a special treat" precisely because he was a big fan of the travel pod. (Star Trek: Communicator issue 136, p. 34)
The gray of the inspection pod's exterior is similar but different to the gray on the hull of the Columbia NX-02. Doug Drexler commented, "The gray on the pod is not a match for the NX. It is actually brighter."
Doug Drexler, who likened the inspection pod to a "space jeep", pointed out, "The capsule configuration suggests that these jeeps were launched into orbit on the top of atlas-like missiles." Not only would this way of shuttling the pods into orbit be an inexpensive method but Drexler also believes that, in particular, the pod's "aerodynamic nose cone shape" indicated the probability of this one-way travel method being used. It is also Drexler's opinion that the missiles would commonly be recovered and reused. He further speculated about the inspection pods, "Once [in orbit] they were taken to an orbital 'motorpool' where they were outfitted for whatever duty they were most needed for [....] The NX was equipped with two jeeps for handling cargo, repairs and routine maintenance."
John Eaves intended for the black, wedge-shaped component at the front of the inspection pod to be a bumper.