although the disclosure hereof is detailed and exact to enable those skilled in the art to practice the invention , the physical embodiments herein disclosed merely exemplify the invention , which may be embodied in other specific structure . while the preferred embodiment has been described , the details may be changed without departing from the invention , which is defined by the claims . an accessory mounting mechanism 10 of the present invention may be seen in its component parts in fig1 . the accessory mounting mechanism 10 comprises a lower grommet 12 , an upper grommet 14 , a fastener 16 , and a cap 18 . the accessory mounting mechanism 10 is adapted to secure an accessory 20 to the substrate 22 of a vehicle . note that , as used herein , the term “ substrate ” is used to denote the frame of an automobile , or any other structure to which an accessory 20 need be attached . note also that the substrate 22 may comprise distinct layers , and in addition to a metallic frame , may also include a fiberboard and fabric headliner 24 of the type commonly used to finish the interior of vehicles . the accessory mounting mechanism 10 of the present invention is , in a preferred embodiment , used to mount an accessory 20 commonly referred to as an assist or grab handle to a vehicle . when the accessory mounting mechanism 10 of the present invention is fully assembled , as shown in fig2 it may easily be secured to substrate 22 of a vehicle in a single step , without the need for special tools . [ 0022 ] fig3 illustrates a lower grommet 12 of the present invention . the lower grommet 12 is typically molded of a relatively rigid material such as nylon or acetal . the lower grommet has a generally rectangular body 30 from which depends a retaining structure 32 . this retaining structure 32 may take many forms , but is preferably formed as a post or shaft that has a snap fit feature 34 ( fig1 and 2 ) formed thereon . preferably , the snap fit feature of the retaining structure 32 will comprise flexible tabs , detents , a plurality of flexible , frustoconical vanes , laterally extending wings , or a simple friction fit , where suitable . where desirable , an additional stem 36 ( see also fig1 and 2 ) may be formed adjacent the retaining structure 32 in order to prevent rotation of the lower grommet 12 when it is assembled with the substrate 22 of a vehicle . the anti - rotation stem 36 may be a simple , smooth shaft , or may include a snap fit type structure ( not shown ) that will assist in retaining the lower grommet 12 to the substrate 22 . the retaining structure 32 and the stem 36 , if one is present , are adapted for insertion into bores 23 a and 23 b , respectively , formed through the relatively thin walled substrate 22 of a vehicle . note that in some instances the retaining structure 32 and the stem 36 will be lengthened so as to extend through the headliner 24 and yet still engage bores 23 a and 23 b formed through the substrate 22 . the body 30 of the lower grommet 12 has a bore 38 formed therethrough that extends downwardly into the retaining structure 32 . this bore is sized to receive the shaft of the fastener 16 therein . note that the bore is sized so as to securely retain the shaft of the fastener 16 therein , i . e ., the bore provides purchase for threads or includes snap fit type features in order to retain the fastener 16 therein . the upper surface of the lower grommet 12 may have a plurality of registration tabs 40 ( see , e . g ., fig3 ) extending upwardly therefrom . these tabs 40 may have any suitable shape or form , the only requirement being that the tabs 40 mate with complementary bores , cutouts , or channels formed in the undersurface of the upper grommet 14 so as to securely register the lower and upper grommets 12 , 14 . note that the registration tabs 40 may be omitted if so desired . a preferred embodiment of the upper grommet 14 is illustrated in fig4 . the upper grommet 14 comprises a base 42 and a superstructure 44 that is positioned above the base 42 upon side plates 46 . a slot 48 that can best be seen in fig6 and 7 exists between the superstructure 44 and the base 42 of the upper grommet 14 . this slot 48 is sized so as receive an end 50 ( fig1 ) of an accessory 20 . typically the end 50 of the accessory 20 will have a bore or hole 52 formed therethrough that provides for the connection of the accessory 20 to the accessory mounting mechanism 10 . a bore 54 is formed entirely through the base 42 and superstructure 44 of the upper grommet 14 and intersects the slot 48 at a location that allows the hole 52 in the accessory end 50 to be aligned therewith . when the upper grommet 14 is registered with the lower grommet 12 , the bore 54 of the upper grommet 14 will align with the bore 38 formed in the lower grommet 12 . once the upper grommet 14 is registered with the lower grommet 12 , the accessory end 50 is inserted into the slot 48 of the upper grommet and the fastener 16 is inserted into bore 54 in the upper grommet , through hole 52 in the accessory end , and into bore 38 of the lower grommet 12 so as to secure the upper grommet 14 to the lower grommet 12 while simultaneously securing the accessory 20 to the upper grommet 14 . note that the fastener 16 is preferably a threaded fastener , but may have any suitable configuration , so long as the fastener 16 will suffice to secure the lower and upper grommets 12 , 14 to one another while retaining the end 50 of the accessory 20 therein . assist or grab handle accessories 20 currently in use typically have two positions . the first position of the accessory 20 is referred to as a stowed position in which the accessory 20 lays flat against a headliner 24 of the vehicle . the accessory 20 is pulled away from the headliner 24 of the vehicle so that a passenger or driver of the vehicle may insert their hand between the accessory 20 and the headliner 24 in the accessory &# 39 ; s 20 second position . in order to facilitate the positioning of the accessory 20 in these two positions , the upper grommet 14 is provided with a flexible tab 55 . the hole 52 formed through the accessory end 50 is sufficiently elongate that the end 50 may slide through a slot 48 until such time as the forward portion of the hole 52 is engaged by the flexible tab 55 . in this way , the accessory 20 will be maintained in its first , stowed , or retracted position as seen in fig6 . when a passenger or driver of a vehicle pulls on the accessory 20 , the flexible tab 55 will be displaced , allowing the end 50 to slide out of the slot 48 until the forward portion of the hole 52 engages the shaft of the fastener 16 . when in this position , as shown in fig7 the accessory 20 will be in its second , extended position . note that the flexible tab 55 is not a requisite part of the invention , and may be omitted if so desired . an alternate embodiment of the upper grommet 14 having a somewhat slimmer profile is illustrated in fig5 . the embodiment of fig5 is adapted to receive a larger cap 18 that likely covers then entire upper grommet 14 , whereas the embodiment of the upper grommet 14 of fig4 is better adapted to be at least partially exposed . note that the embodiments of the upper grommet 14 illustrated in fig4 and 5 are functionally the same . the cap 18 of the present invention serves to obscure and protect the lower and upper grommets 12 , 14 once they have been secured to one another and the accessory end 50 is retained therein . the cap 18 is constructed and arranged to be secured to the upper grommet 14 in a snap fit arrangement . this snap fit arrangement may take any suitable form that will securely attach the cap 18 to the upper grommet 14 . in a preferred embodiment , best seen in fig1 and 2 , the cover 18 forms a dome - like structure having a single aperture 56 formed therein . the end 50 of the accessory 20 must be passed through this aperture 56 before the end 50 is inserted into the slot 48 in the upper grommet 14 . then , after the upper and lower grommets 14 , 12 have been secured to one another so as to retain the end 50 of the accessory 20 therein , the cap 18 is slid down the accessory 20 to be engaged with the lower and upper grommets 12 , 14 . in the preferred embodiment of the present invention , the inner surface of the cap 18 is provided with a lip ( not shown ) that engages ears 43 ( fig4 ) of the upper grommet 14 . the edge of the cap 18 opposite the lip is constructed and arranged to create an interference fit with the end of the upper grommet 14 opposite ears 43 to create a typical snap fit arrangement . note that the lower grommet 12 may be constructed and arranged to provide the means for attaching the cap 18 to the accessory mounting mechanism 10 of the present invention in lieu of the upper grommet 14 . it is to be understood that the cap 18 may have many different shapes , each shape adapted to best complement the interior of a vehicle into which it is installed . in addition , the aperture 56 may be formed as a slot so as to allow the cap 18 to be maintained separately from the upper and lower grommets 14 , 12 until after the grommets have been secured to one another so as to retain the end 50 of the accessory therein . in addition , where the exterior of the sidewalls 46 of the upper grommet 14 have been adapted to be visible after final installation of the accessory mounting mechanism 10 , the cap 18 may have an abbreviated shape adapted solely to cover that portion of the upper grommet wherein the bore 54 and flexible tab 54 are located . in use , the accessory mounting mechanism 10 is typically assembled remotely from the vehicle with which it will ultimately be assembled . the assembled accessory mounting mechanism 10 , as best seen in fig2 is then brought to a vehicle and installed by inserting the retaining structure 32 into a bore 23 a formed in the substrate 22 of the vehicle . where present , the stem 36 will be inserted into bore 23 b . as the retaining structure 32 , and where present , the stem 36 , are constructed and arranged to maintain a snap fit with the substrate 22 , the accessory mounting mechanism 10 may be assembled simply by applying pressure to the cap 18 directly over the retaining mechanism 32 and stem 36 . it is to be understood that , where necessary , multiple accessory mounting mechanisms 10 may be employed to secure an accessory 20 to the substrate 22 of a vehicle . for example , in the preferred embodiment of the present invention , the accessory mounting mechanism 10 is adapted to secure a single end of an assist or grab handle 20 to the substrate 22 of a vehicle . as this accessory 20 typically has two ends , two accessory mounting mechanisms 10 will be utilized to secure the accessory 20 to the substrate 22 of the vehicle . it will be appreciated that additional accessory mounting mechanisms , or indeed , fewer , may be utilized to secure various and sundry accessories 20 to the substrate 22 . the foregoing is considered as illustrative only of the principles of the invention . furthermore , since numerous modifications and changes will readily occur to those skilled in the art , it is not desired to limit the invention to the exact construction and operation shown and described . while the preferred embodiment has been described , the details may be changed without departing from the invention , which is defined by the claims .