| Schedule of property and equipment |
| | |
March 31,
2019 | | |
December 31,
2018 | |
| Shop machinery and equipment | |
$ | 104,468 | | |
$ | 87,534 | |
| Computers and electronics | |
| 38,961 | | |
| 32,093 | |
| Office furniture and fixtures | |
| 37,814 | | |
| 37,814 | |
| Leasehold improvements | |
| 26,473 | | |
| 19,514 | |
| | |
| 207,716 | | |
| 176,955 | |
| Less - accumulated depreciation | |
| (132,528 | ) | |
| (123,725 | ) |
| | |
$ | 75,188 | | |
$ | 53,230 | |
|